P1446 Code: Clean the Nissan EVAP Vent Valve Before You Replace

P1446 Code: Clean the Nissan EVAP Vent Valve Before You Replace

STOP — Before You Buy a $150 New Vent Valve, Spend 15 Minutes Cleaning the Existing One. Dust and Carbon Are the Actual Cause in 25-30% of Nissan P1446 Cases.

P1446 Code: Clean the Nissan EVAP Vent Valve Before You Replace

P1446 is a Nissan/Infiniti-specific code with a distinctive reverse-misdiagnosis pattern. The Check Engine Light comes on, a fuel vapor smell appears, and shops sometimes quote $200-$400 valve replacement. But about 25-30% of P1446 cases respond to simple cleaning — the vent valve is exposed to road dust and water under the rear of Nissan vehicles, and accumulated contamination prevents the valve plunger from sealing properly. 15 minutes with $5 of electrical contact cleaner restores function in many cases. Only after cleaning fails should replacement be authorized.

Updated June 2026 7 min read DIY Difficulty: Easy Fix Cost: $0 – $250
⚡ QUICK ANSWER

P1446 is a Nissan/Infiniti-specific code meaning "EVAP Canister Vent Control Valve Close" — the ECM detected that the canister vent valve can't close properly when commanded. Technical mechanism: the EVAP vent valve is normally OPEN (allowing fresh air into the carbon canister); the ECM commands it CLOSED briefly during EVAP leak diagnostics to create a sealed system for pressure-decay testing. If the valve fails to close (stuck open), leak diagnostics fail and P1446 sets. Cause distribution: about 40-50% faulty vent valve from dust/carbon/water contamination ($40-$150 OEM replacement), 15-20% EVAP pressure sensor failure ($50-$150), 10-15% wiring/connector corrosion ($5-$60), 10-15% canister saturated with water ($80-$250), 5-10% vacuum tube blockage ($10-$30), 5-10% EVAP system small leak ($20-$100), under 5% ECM failure ($400-$1,500). The 15-minute money-saving test: remove valve, clean with electrical contact cleaner, test plunger movement — about 25-30% of P1446 cases resolve completely with cleaning alone.

What Does P1446 Actually Mean?

P1446 is a manufacturer-specific code used primarily by Nissan and Infiniti (and occasionally on early-2000s VW/Audi models). It indicates the ECM detected that the EVAP Canister Vent Control Valve cannot properly close when commanded. To understand why this matters, consider the EVAP system's job: capture fuel vapors from the gas tank and burn them in the engine instead of releasing them to atmosphere. The system has several components — fuel tank, charcoal canister (absorbs vapors), purge valve (releases vapors to engine intake), and the vent valve (allows fresh air into the canister).

The vent valve is unique among EVAP components — it spends almost all of its operating life OPEN. The ECM commands it CLOSED only briefly during diagnostic leak-detection cycles. The diagnostic logic: ECM closes vent valve → EVAP system becomes sealed → ECM monitors system pressure → small natural pressure changes confirm system integrity → ECM concludes "no leaks" or "leak detected." If the vent valve can't close, the diagnostic can't run; the ECM eventually sets P1446 indicating "I can't perform leak diagnostics because the vent valve won't seal." Importantly, P1446 doesn't say "there's a leak" — it says "I can't test for leaks."

The Nissan vent valve design is a solenoid-operated valve: ECM sends 12V → coil energizes → plunger moves to seal the vent port. When ECM removes power, a spring returns the plunger to the OPEN position. Failure modes: (1) coil burned out — no movement possible; (2) plunger sticks in OPEN position from dust/carbon/corrosion — coil energizes but plunger can't move; (3) seal degraded — plunger moves but doesn't seal properly; (4) electrical connection issue — coil doesn't receive proper voltage. Each failure mode is diagnosed differently, but most respond to the same fix: cleaning, then replacement if cleaning fails.

P1446 vs P0446 vs P0449 — Nissan vs generic codes: P1446 = Nissan/Infiniti-specific code for "EVAP Canister Vent Control Valve Close" (this article — specific failure mode). P0446 = Generic OBD-II code for "EVAP Vent Control Circuit Malfunction" (broader electrical fault — same valve, different ECM detection criteria). P0449 = Generic OBD-II code for "EVAP Vent Valve/Solenoid Circuit" (similar generic version). The same physical valve on a Nissan can trigger P1446 (when Nissan's manufacturer-specific tests catch the closure-specific failure) OR P0446 (when generic electrical tests catch it) — depending on which test runs first and what specific signature the failure produces. Diagnostic approach overlaps significantly for all three codes. P1446 commonly co-occurs with: P0442 (EVAP small leak — vent valve can't close to run leak test), P0455 (EVAP large leak), P1448 (EVAP pressure sensor), P1444 (EVAP purge volume control). Multiple EVAP codes set together often indicate a complete EVAP service is needed.
Critical — never authorize EVAP system replacement on P1446 without trying cleaning first: The P1446 misdiagnosis pattern is consistent across shops — see Nissan with EVAP code, quote $200-$400 for "vent valve assembly replacement," and miss that simple cleaning would have fixed 25-30% of cases. Required from any shop before authorizing valve replacement over $150: documented valve resistance test (showing measured ohms vs 22-26 ohm spec), documented cleaning attempt with electrical contact cleaner, bidirectional valve activation test result. If "we diagnosed bad EVAP vent valve, needs replacement" is the entire diagnostic record without documented cleaning attempt, request the cleaning be performed first. The 15-minute cleaning costs $5-$10 in materials; if it doesn't restore function, replacement is justified. About 25-30% of Nissan P1446 cases will save the customer $50-$200 in unnecessary parts.

What Are the Symptoms of P1446?

P1446 has minimal driveability symptoms but distinctive emissions-related effects:

Check Engine Light — almost always the ONLY engine symptom
Strong fuel vapor smell — especially near rear of vehicle
Emissions test failure — primary reason owners notice the code
Gas pump clicks off repeatedly — refueling difficulty
Hissing sound after refueling — pressurized tank releasing
Slight MPG drop — 1-2 MPG decrease
Strong odor in hot weather — vapor expansion accelerated
NO engine performance impact — runs normally throughout
The "fuel smell near rear of vehicle" diagnostic tell: P1446 has a distinctive fuel vapor odor pattern — strongest near the rear of the vehicle (where canister is mounted on most Nissans), particularly noticeable after refueling, on hot days, and in enclosed spaces like garages. If you smell raw gasoline near your Altima/Maxima/Infiniti's rear bumper area and the CEL is on, P1446 fits the pattern. The smell is caused by escaping fuel vapors that should have been captured by the sealed EVAP system — but because the vent valve can't seal, the system isn't pressurizing properly and vapors escape through the vent. The smell is unpleasant but not directly dangerous; the bigger concern is the failed emissions inspection and gradually worsening fuel economy.

Is P1446 Code Serious?

Low-moderate severity — minimal mechanical concerns; primarily emissions compliance issue. Address before next emissions inspection but no urgency for engine protection.

Failed emissions tests → blocks vehicle registration renewal
Strong fuel vapor smell → unpleasant but not dangerous
Refueling problems → pump click-off issues
Slight MPG loss → 1-2 MPG drop accumulates
No engine damage → EVAP system isolated from engine performance
Diagnostic misdiagnosis risk → MODERATE; cleaning often skipped

The defining feature of P1446: low mechanical severity, moderate financial misdiagnosis risk. Many Nissan owners have paid $200-$400 for EVAP valve replacement when 15 minutes of cleaning would have fixed the issue for $5 in supplies. The diagnostic sequence is dramatically cheaper than the alternative — clean first, only replace if cleaning fails. Most P1446 cases resolve under $150 DIY when proper diagnostic procedure is followed.

Severity rating: 🟢 Low (mechanical). 🟡 Moderate (financial misdiagnosis risk). The mechanical seriousness is genuinely low — no immediate engine damage; only emissions and minor convenience impact. The financial seriousness is moderate because of the cleaning-vs-replace pattern: shops often skip the cleaning step and quote full replacement. Always attempt Step 3 cleaning before authorizing any parts work over $50. Address P1446 within 1-2 months at most — there's no rush for engine protection, but emissions inspection cannot be passed until cleared.

What Causes a P1446 Code? (Ranked by Frequency)

Nissan EVAP system diagram showing the canister vent control valve, charcoal canister, purge valve, fuel tank, and connecting hoses that trigger P1446 when the vent valve cannot close for leak diagnostics
Figure 1: EVAP system layout — the canister vent control valve (the P1446 failure point) sits on the charcoal canister and is exposed to road dust and water in its underbody mounting location.

Cause distribution heavily favors the valve itself, with the cleaning option being the key first step:

1

Vent Valve Stuck Open from Dust/Carbon (40-50% of Cases)

The dominant P1446 cause. The vent valve's normally-open design means dust and road grime enter through the fresh-air intake; over years, accumulation prevents the plunger from seating properly. Some of these cases respond to cleaning (Step 3); others require replacement when contamination has caused permanent mechanical damage. Distinctive: visible dust/carbon on valve when removed; plunger doesn't move freely; high-mileage Nissan 100,000+ miles; vehicle driven in dusty conditions; resistance test in spec (electrical OK) but valve doesn't seal. Fix: clean valve first ($5-$10 in supplies + 15 minutes — works in 25-30% of cases); if cleaning fails, replace with OEM Nissan valve ($40-$150 + 30 minutes labor).

Fix: $5–$150 clean or replace
2

EVAP Pressure Sensor Failure (15-20%)

The EVAP system uses a pressure sensor to detect leaks (closed system should hold pressure for diagnostic period). If the pressure sensor fails or its signal is corrupted, the ECM can't perform diagnostics and may set P1446 even though the vent valve itself is fine. Distinctive: P1446 + intermittent pattern; vent valve tests good (resistance and bidirectional); pressure sensor reading erratic on live data; vehicle 80,000+ miles. Fix: replace EVAP pressure sensor ($50-$150 OEM + 30 minutes labor — typically mounted on top of fuel tank or near canister). About 15-20% of P1446 cases involve the pressure sensor.

Fix: $50–$150 pressure sensor
3

Wiring or Connector Corrosion (10-15%)

Nissan EVAP wiring routes under the vehicle in exposed underbody locations. Salt-belt exposure (Northeast US, Canada) causes connector pin corrosion at the vent valve and pressure sensor connectors. Distinctive: visible green/white sulfate on connector pins; intermittent P1446; wiggle test reveals voltage shifts; salt-belt vehicle 5+ years old. Fix: clean connector with electrical contact cleaner + dielectric grease ($5-$10); splice damaged wire if needed ($10-$30); install pigtail connector kit for severe damage ($10-$30).

Fix: $5–$60 wiring repair
4

EVAP Canister Water Saturation (10-15%)

The Nissan canister mounting location (under vehicle, near rear) exposes the canister to water spray during driving. Over years, water gradually saturates the carbon inside the canister; saturated carbon can't absorb fuel vapors properly; pressure changes become abnormal; P1446 sets. Distinctive: canister sloshes when shaken (water inside); white residue around canister mounting; vehicle frequently driven in heavy rain or coastal areas. Fix: replace canister assembly ($80-$250 OEM Nissan + 1-2 hours labor). Often combined with vent valve replacement on heavily-affected vehicles.

Fix: $80–$250 canister
5

Vacuum Tube Blockage (5-10%)

Rubber vacuum tubes connecting the vent valve to the canister and main EVAP system can become blocked by debris (mud, insect nests, dirt) or kinked from underbody impacts. Blocked tubes prevent proper pressure equalization; P1446 sets. Distinctive: visual inspection reveals tube blockage or damage; vehicle driven off-road or in extreme weather; sometimes obvious during routine underbody inspection. Fix: clean or replace affected tubes ($10-$30 in materials).

Fix: $10–$30 hose work
6

EVAP System Small Leak (5-10%)

A small leak elsewhere in the EVAP system can prevent proper diagnostic completion, indirectly triggering P1446. Common leak sources: gas cap seal aged (replace cap $10-$25), fuel filler neck deteriorated, EVAP hose cracked. Distinctive: P1446 + P0442 (small leak) co-occur; smoke test reveals leak source; gas cap visibly worn. Fix: address the actual leak source first; P1446 typically clears once leak is fixed.

Fix: $10–$100 leak repair
7

ECM Failure or Software Issue (Rare, <5%)

ECM internal failure affecting the EVAP control circuit, or ECM software bug. Distinctive: multiple EVAP codes set; sensors and components all test good; manufacturer TSB may exist. Fix: ECM reflash with updated software ($0-$300 dealer service) OR ECM replacement ($400-$1,500 + Nissan programming). Less than 5% of P1446 cases — diagnose by exclusion only.

Fix: $0–$1,500 ECM service

What You'll Need

Tools

  • OBD2 scanner with bidirectional EVAP + Nissan coverage iCarzone UR800 ›
  • Digital multimeter (DVOM with ohms / resistance)
  • Jack and jack stands (to access valve under vehicle)
  • Basic hand tools (sockets, screwdrivers)
  • Smoke machine (optional — for EVAP leak detection)

Possible Parts & Supplies

  • Electrical contact cleaner $5–$10
  • OEM Nissan EVAP canister vent valve $40–$150
  • EVAP pressure sensor (if needed) $50–$150
  • EVAP canister assembly (if saturated) $80–$250
  • Replacement gas cap $10–$25
  • Vacuum hose set $10–$30
  • Dielectric grease $5–$10
Recommended Diagnostic Tool for P1446

iCarzone UR800 — 5" LCD OBD2 Diagnostic Scanner

★★★★★ Bidirectional EVAP · Live Pressure · Nissan Coverage

5-inch LCD diagnostic scanner with quad-core 1.3GHz processor at $299.99 — well-suited to Nissan/Infiniti EVAP system diagnosis. Key features for P1446: bidirectional EVAP canister vent valve activation on Nissan/Infiniti platforms (commands the vent valve ON/OFF to verify mechanical response — essential for confirming whether ECM commands reach the valve and whether the valve responds); EVAP system pressure live data (verify pressure changes when vent valve commanded closed — catches the "valve clicks but doesn't seal" marginal failures); EVAP leak test routine on Nissan-compatible vehicles (helps identify whether P1446 is primary issue or secondary to actual EVAP leak); freeze frame data showing exact conditions when P1446 triggered (helps diagnose intermittent valve issues); ECU adaptation reset (sometimes needed post-repair on Nissan platforms). Broad Nissan/Infiniti coverage including Altima (2007-2018 — highest-volume P1446 platform with documented vent valve issues), Maxima (2009-2018), Sentra/Versa, Frontier/Pathfinder/Xterra, Murano/Rogue, Quest minivan, Cube, Juke, and Infiniti G35/G37/Q50/Q60/M35/M37/M45/EX35/EX37/FX35/FX37. The UR800's Nissan-specific bidirectional EVAP + pressure monitoring combination is the key feature set for P1446 diagnosis — without it, distinguishing "clean and recover" cases from "must replace" cases requires expensive guess-and-replace approach.

$299.99
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How Do You Fix a P1446 Code?

Follow these steps in order. Step 3 (15-minute cleaning) is the reverse-misdiagnosis killer — costs $5-$10 in supplies and fixes 25-30% of cases without any parts purchase.

P1446 Diagnostic Flowchart — Decision Tree

P1446 Diagnostic Flowchart Decision tree starting with scan codes and valve location, resistance test, 15-minute cleaning step, bidirectional activation, canister and hose inspection, and targeted repair. START · Scan codes + locate valve Step 2: DVOM RESISTANCE TEST Nissan spec 22-26 ohms — open/short = replace OL or short? Step 6 Step 3: 15-MIN CLEANING (reverse-misdiagnosis) Remove + clean with contact cleaner Fixes 25-30% — saves $50-150 vs replace Step 4: BIDIRECTIONAL ACTIVATION Scanner click test + pressure response Step 5: Canister + hose inspection Shake canister; trace hoses for damage Step 6: Replace valve if cleaning failed $40-150 OEM Nissan part + 30-min DIY P1446 cleared + emissions pass
Figure 2: P1446 diagnostic decision tree — Step 3 (15-minute cleaning) is the reverse-misdiagnosis killer that catches 25-30% of cases that respond to cleaning rather than replacement. Always attempt cleaning before authorizing parts replacement over $50.
  • 1

    Scan All Codes and Locate the Nissan EVAP Vent Valve

    Plug in scanner, record all codes. P1446 commonly appears with companion codes:

    • P0442 — EVAP Small Leak (often co-occurs — vent valve can't close to perform leak test)
    • P0455 — EVAP Large Leak (gas cap or hose alongside vent valve)
    • P0456 — EVAP Very Small Leak
    • P0457 — EVAP Leak from gas cap
    • P1444 — EVAP Purge Volume Control Valve
    • P1448 — EVAP Pressure Sensor
    • P1490 — EVAP Vacuum Cut Valve Bypass

    Locate the EVAP canister vent valve on YOUR specific Nissan:

    • Altima 2007-2018: on EVAP canister under rear of vehicle near spare tire well
    • Maxima 2009-2018: under rear bumper near canister
    • Sentra/Versa: under rear of vehicle near gas tank
    • Frontier/Pathfinder/Xterra: frame-mounted canister assembly, valve on canister body
    • Murano: under rear cargo area floor
    • Rogue: under spare tire
    • Infiniti G35/G37: similar to Maxima layout — rear underbody

    The valve is a small cylindrical solenoid (1-2 inches long) attached to the EVAP canister with a single mounting bolt and electrical connector.

  • 2

    Test Valve Resistance with DVOM

    First electrical test — quickly identifies fully failed valves:

    Procedure:

    • Vehicle parked safely; key OFF
    • Raise vehicle on jack stands to access valve
    • Disconnect electrical connector at EVAP vent valve
    • Set DVOM to ohms (Ω) on 0-200 ohm scale
    • Probe across valve terminals on the VALVE side

    Expected resistance — Nissan/Infiniti vent valve:

    • 22-26 ohms typical Nissan/Infiniti specification
    • Verify with vehicle service manual for your specific year
    • Room temperature reading (not after operation)

    Interpreting results:

    • 22-26 ohms (in spec) = valve electrically OK; mechanical issue likely; proceed to Step 3 cleaning
    • Infinite resistance / OL = valve coil open-circuit (burned out); skip to Step 6 replacement
    • Below 5 ohms = valve internally shorted; skip to Step 6 replacement
    • Significantly out of spec (e.g., 50 ohms) = valve degrading; replacement recommended

    Also verify harness side:

    • With key ON, multimeter probe harness POWER pin
    • Should read 10-14V (battery voltage)
    • If 0V = wiring between ECM/fuse and connector open; different problem than valve

    About 20-25% of P1446 cases are diagnosed at resistance test alone — confirming dead valves that need replacement.

  • 3

    The 15-Minute Clean-First Reverse-Misdiagnosis Test

    Critical step that catches 25-30% of P1446 cases that respond to cleaning rather than replacement:

    The principle:

    • The EVAP vent valve is mounted in an exposed underbody location
    • Dust, road grime, and small amounts of water enter the canister fresh air intake
    • Over 60,000-150,000 miles, dust accumulates inside the valve mechanism
    • The valve sticks open (can't close on command)
    • Cleaning removes contamination and restores function

    Procedure:

    • Vehicle safely raised; valve already disconnected from Step 2
    • Remove valve from canister (typically 1-2 bolts or quick-release tab)
    • Visual inspection: look for dust accumulation, carbon staining, white crystalline residue (water damage), rust on metal housing

    Cleaning procedure:

    • Spray electrical contact cleaner generously into BOTH ports of valve
    • Gently push plunger in and out with small screwdriver while cleaner flows through
    • Tap valve body firmly on wooden surface to dislodge loose contamination
    • Spray with clean compressed air until cleaner residue evaporates
    • Allow to dry 10 minutes
    • Test plunger movement — should move freely without binding

    Reassemble and test:

    • Reinstall and reconnect electrically
    • Clear codes with scanner
    • Drive 30 miles through varied conditions (highway, stop-and-go, multiple refueling cycles)
    • Re-scan to verify P1446 doesn't return
    Success rate: about 25-30% of P1446 cases resolve completely with cleaning alone. The 15-minute investment costs $5-$10 in cleaner and saves $50-$150 replacement cost. If cleaning fails (P1446 returns within 30 miles), proceed to Step 6 replacement — the valve is mechanically failed and replacement is justified. NEVER skip this step before authorizing parts replacement.
  • 4

    Bidirectional Valve Activation Test on Scanner

    Verify ECM command and valve mechanical response with scanner-controlled activation:

    Procedure:

    • Engine OFF, key ON
    • Valve reinstalled and reconnected (from Step 3 cleaning)
    • On scanner: navigate to bidirectional control / actuation tests / EVAP system / canister vent valve
    • Select EVAP Canister Vent Valve Activation (UR800 supports this on most Nissan/Infiniti platforms)
    • Command valve CLOSED
    • Listen for distinct 'click' from valve location
    • Observe scanner status feedback

    Interpreting results:

    • Normal: distinct audible click on each ON/OFF command; status feedback confirms state change; cycle test (rapid ON/OFF) shows consistent response
    • No click on command = valve electrically dead (already confirmed in Step 2) OR ECM not commanding (rare wiring/driver issue)
    • Click present but P1446 returns = mechanical sticking beyond electrical (plunger physically stuck despite coil operating)
    • Inconsistent response = intermittent connection or partially failing solenoid

    Pressure response verification (critical):

    • Monitor EVAP pressure sensor reading during commanded valve close
    • Pressure should drop slightly as system seals (small change but detectable)
    • No pressure change despite click = valve clicking but not actually sealing the vent — partial failure beyond cleaning's ability to fix

    The bidirectional + pressure monitoring combo on UR800 catches marginal failures that resistance test alone misses.

  • 5

    Inspect Canister Saturation and Connecting Hoses

    Check for water-saturated canister and hose issues that can cause or accompany P1446:

    Canister water saturation test:

    • Vehicle still raised on stands
    • Locate EVAP canister (large black plastic box near vent valve)
    • Carefully detach canister from mounting
    • Pick up canister and tilt — should be LIGHT
    • Shake canister gently and listen — water sloshing inside indicates saturation

    Why saturated canisters cause P1446:

    • Water-soaked carbon can't absorb fuel vapors normally
    • Pressure changes in saturated system trigger false 'cannot close' signals
    • Valve mechanism gets contaminated by moisture

    If canister sloshes when shaken = replacement required ($80-$250 OEM canister assembly).

    Hose inspection:

    • Trace all rubber hoses from canister to vent valve, purge valve, fuel tank, engine
    • Look for cracks in rubber (UV/age damage), kinked sections (collapse), disconnections, hose clamps loose or missing
    • Common findings: brittle rubber hoses on Nissan 100,000+ miles routinely fail; fresh-air intake hose to vent valve particularly prone to dust/water intrusion
    • Fix damaged hoses with high-temp fuel-vapor-rated replacement ($10-$30)

    Pressure sensor check:

    • While accessing canister, inspect EVAP pressure sensor connector for corrosion
    • 15-20% of P1446 cases involve pressure sensor secondary issue
    • Clean connector + dielectric grease if corrosion visible
  • 6

    Replace Vent Valve and Verify (If Cleaning Failed)

    If Step 2 resistance test failed (electrical fault) OR Step 3 cleaning didn't resolve the code (mechanical fault beyond cleaning), replace with OEM Nissan part:

    Order OEM EVAP canister vent valve by VIN:

    • Altima 2007-2018: Nissan 14935-7Y00B (most common)
    • Maxima 2009-2014: Nissan 14935-CN00B
    • Frontier/Pathfinder 2005-2015: Nissan 14935-EA00B
    • Always verify exact part number by VIN — multiple supersession versions exist

    Replacement procedure:

    • Vehicle still on jack stands
    • Remove old valve (typically 1-2 mounting bolts or quick-release clip)
    • Inspect mounting interface for damage or contamination; clean if necessary
    • Apply small amount of dielectric grease to electrical connector contacts
    • Install new valve with new O-ring (typically supplied with OEM)
    • Torque mounting bolt to spec (5-7 ft-lb — gentle)
    • Reconnect electrical connector; verify locking tab engaged

    Post-repair verification:

    • Clear codes with scanner
    • Perform EVAP system test via scanner if available (UR800 supports this on Nissan/Infiniti)
    • Drive 50+ miles through 2-3 drive cycles
    • Ensure fuel cap is fully tightened on next fill-up
    • Re-scan to verify P1446 doesn't return

    About 40-50% of P1446 cases resolve at this step with $40-$150 in parts. If P1446 returns after replacement, investigate canister saturation (Step 5) and EVAP pressure sensor — sometimes multiple components fail simultaneously on high-mileage Nissan vehicles.

How Much Does P1446 Cost to Fix?

P1446 cost varies by root cause — from $0 (cleaning) to $250 (canister replacement). The proper diagnostic sequence determines which category before any parts purchase.

Repair DIY Cost Shop Cost You Save Type
Diagnostic — valve resistance + visual $0 $120–$200 Up to $200 5-Min Free Test
Valve cleaning with contact cleaner (FIXES 25-30% of cases) $5–$10 Often skipped Up to $300 15-Min Cheap Fix
EVAP canister vent valve replacement (FIXES 40-50% of cases) $40–$150 $150–$350 Up to $300 DIY Easy
EVAP pressure sensor replacement (FIXES 15-20% of cases) $50–$150 $150–$350 Up to $300 DIY Moderate
Wiring / connector cleanup $5–$30 $80–$200 Up to $195 DIY Easy
EVAP canister replacement (saturated, 10-15%) $80–$250 $250–$500 Up to $420 DIY Moderate
Vacuum tube / hose replacement $10–$30 $80–$150 Up to $140 DIY Easy
Gas cap replacement (if leak found) $10–$25 $30–$60 Up to $50 DIY Trivial
ECM reflash or replacement (rare) — $300–$1,500 — Last Resort
The diagnostic ROI: The $299 UR800 scanner with Nissan-specific bidirectional EVAP control + pressure monitoring is the right tier for Nissan/Infiniti diagnostic work — pays for itself on multiple cases. For P1446 specifically, the bidirectional capability allows confirming whether the valve responds to ECM commands without test-driving the vehicle — eliminating the "drive 50 miles to see if cleaning worked" wait time on each diagnostic cycle. The UR800 also handles other Nissan-specific codes (P0011 VVT, P0335 crank sensor, P0345 cam sensor, P0420 catalyst efficiency, P0507 idle air) — making it a multi-purpose investment for any Nissan owner with multiple emissions or sensor issues over the vehicle's lifetime.

Per the EPA's emissions standards ↗ EPA Vehicle Emissions I/M Program, a vehicle with active P1446 will FAIL OBD-II emissions inspection in most states. EVAP components are covered under federal emissions warranty for the first 8 years / 80,000 miles. Verify with your Nissan dealer using VIN before paying out of pocket on newer vehicles — many P1446 cases on covered vehicles qualify for free vent valve replacement under emissions warranty.

Which Vehicles Are Most Prone to P1446?

P1446 is a Nissan/Infiniti-specific code. Nissan Altima 2007-2018 and Infiniti G35/G37 2003-2013 are the highest-volume P1446 platforms. Deep-dives below.

Make Model / Engine Years Primary Cause & Notes Risk
Nissan Altima (2.5L QR25, 3.5L VQ35) 2007–2018 Highest-volume P1446 platform; dust/water exposure documented. See Altima deep-dive. Very High
Infiniti G35, G37 (3.5L VQ35, 3.7L VQ37) 2003–2013 Second highest-volume; similar canister design to Maxima. See Infiniti deep-dive. High
Nissan Maxima (3.5L VQ35) 2009–2018 Frame-mounted canister exposed to road spray; valve dust accumulation. High
Nissan Sentra, Versa (1.6L, 1.8L, 2.0L) 2007–2018 Common P1446 platform; similar valve design to Altima. Medium
Nissan Frontier, Pathfinder, Xterra (4.0L VQ40) 2005–2015 Truck-mounted canister gets more dust/water exposure; off-road driving accelerates. High
Nissan Murano, Rogue (2.5L QR25, 3.5L VQ35) 2008–2015 Standard P1446 pattern; valve under rear cargo area. Medium
Infiniti M35, M37, M45, Q50, Q60 2003–2018 Premium Nissan platforms; same EVAP system architecture. Medium
VW / Audi Early 2000s models (limited) 2000–2005 Some European models use similar manufacturer-specific code. Low

P1446 on Nissan Altima 2007-2018 (Highest-Volume Platform)

Nissan Altima 2007-2018 is the dominant P1446 platform — both because of high production volume AND specific EVAP design vulnerabilities:

1. Dust/water intrusion (the dominant pattern). Nissan mounts the EVAP canister and vent valve under the rear of the vehicle near the spare tire well — a location exposed to: road spray from the rear wheels, mud/dust on unpaved roads, water from rain and standing puddles. Over 80,000-130,000 miles, contamination accumulates inside the valve. The early Altima 2007-2010 valve design had less filtration than later models; these years are particularly prone to P1446. Distinctive: Altima VIN + 100,000+ miles + obvious dust visible on valve when removed + resistance test in spec (electrical OK) + plunger sticks when pushed manually. Fix: Step 3 cleaning is the highest-payoff intervention — about 40-50% of Altima 2007-2010 cases respond to cleaning alone; later 2011-2018 models with improved valve design have lower cleaning success rate (25-30%) but cleaning still worth trying first.

2. Common companion issues. Altima P1446 frequently co-occurs with: P0442 (small leak — vent valve can't seal for diagnostic), P1448 (EVAP pressure sensor — same exposed location), brittle rubber hoses (UV/age damage). Fix multiple Altima issues simultaneously: clean and inspect vent valve, replace any obviously failed hoses ($10-$30), check EVAP pressure sensor connector for corrosion. Often a single $100 service visit addresses multiple Altima EVAP issues.

3. Nissan TSB and warranty extensions. Nissan issued multiple TSBs covering EVAP issues on Altima 2007-2015. Some California Altima owners qualify for free emissions warranty replacement. Check NHTSA.gov by VIN for current applicable bulletins.

Nissan Altima action plan: Step 3 cleaning FIRST — Altima 2007-2010 cleaning success rate is 40-50%, dramatically higher than the typical 25-30%. Use Nissan-OEM electrical contact cleaner (some aftermarket cleaners damage rubber seals). Also clean the canister fresh-air intake hose at the same time (often has dust/insect debris). Check NHTSA.gov for VIN-specific TSBs — Nissan has issued multiple bulletins covering Altima EVAP service. Plan $5-$150 for most Altima P1446 cases; don't pay $300+ shop quotes without insisting on cleaning first.

P1446 on Infiniti G35 / G37 2003-2013 (Premium Variant Pattern)

Infiniti G35/G37 (3.5L VQ35DE and 3.7L VQ37VHR engines) are the second highest-volume P1446 platform, sharing EVAP design with Nissan Maxima:

1. Similar dust/water intrusion pattern. Infiniti G35/G37 use the same Nissan-platform EVAP canister and vent valve, mounted in similar underbody locations. Same failure mechanisms apply: dust accumulation, road spray exposure, valve sticking. Distinctive: G35/G37 VIN + 80,000-150,000 miles + same symptoms as Altima pattern. Cleaning success rate similar to Altima (25-40%).

2. Premium owner expectations. Infiniti owners often face dramatic price differentials between dealer service (Infiniti dealer EVAP service typical $400-$600) and DIY ($5-$150). The cleaning-first approach saves the most money on Infiniti platforms specifically — dealer labor rates make even "simple" EVAP service expensive. Same OEM Nissan part numbers work on Infiniti (just relabeled by VIN). Distinctive: Infiniti owner facing $500+ dealer quote for "EVAP system service" — Step 3 cleaning + Step 6 DIY replacement saves $300-$500.

3. G37 vs G35 differences. The G37 (2008+) has slightly improved EVAP valve design compared to G35 (2003-2007); G35 has higher cleaning-fix success rate due to older more-prone-to-dust valve design. Distinctive: G35 owner = try cleaning aggressively (45-50% success); G37 owner = try cleaning but expect more replacement-needed cases (25-30% success).

Infiniti G35/G37 action plan: Same diagnostic procedure as Altima but expect higher dealer pricing if you choose dealer service. ALWAYS try Step 3 cleaning first — Infiniti dealer service rarely includes cleaning attempt before quoting replacement. OEM Nissan parts work on Infiniti (same part numbers — Infiniti is Nissan's premium brand). Plan $5-$150 for most G35/G37 P1446 cases; ignore dealer quotes over $400 unless cleaning has been attempted and documented.
How to check for a TSB or recall: Visit NHTSA.gov ↗, enter your VIN. Search for "P1446," "EVAP canister vent valve," "EVAP system" + your specific Nissan or Infiniti model. Notable: Nissan has issued multiple TSBs covering EVAP service on Altima 2007-2015 platforms. Some California Nissan/Infiniti owners qualify for extended emissions warranty coverage. Many P1446 cases on covered vehicles qualify for FREE dealer repair worth $200-$500.

Should You DIY or Call a Mechanic?

DIY If You…
  • ✓ Own OBD2 scanner with Nissan-compatible bidirectional EVAP control
  • ✓ Have access to jack and jack stands (or ramp)
  • ✓ Comfortable with basic underbody work
  • ✓ Have a multimeter for resistance testing
  • ✓ Want to save $200-$500 vs Nissan dealer EVAP service
  • ✓ Nissan/Infiniti owner with cleaning-first cost-savings priority
Use a Mechanic If…
  • → Vehicle under emissions warranty (8 yrs / 80,000 mi — FREE coverage)
  • → Multiple EVAP-related codes set across system
  • → Canister replacement required (more complex than valve swap)
  • → ECM reflash needed (dealer service required)
  • → No prior experience with underbody work
  • → Limited workspace for safe jack stand use
Never authorize EVAP valve replacement on P1446 without documented cleaning attempt. This is the most important P1446 protection. Required from any shop before authorizing valve replacement over $150: documented valve resistance test result (showing measured ohms vs 22-26 ohm spec), documented cleaning attempt with electrical contact cleaner, bidirectional valve activation test result, EVAP pressure response measurement. If "we diagnosed bad EVAP vent valve, needs $300 replacement" is the entire diagnostic record without documented cleaning attempt, request cleaning be performed first. The 15-minute cleaning takes $5-$10 in materials — there's no legitimate reason for a shop to skip it. If shop refuses to clean before replacing, find a different shop — about 25-30% of Nissan P1446 cases will save the customer $50-$200+ in unnecessary parts via cleaning. Always check NHTSA.gov for VIN-specific TSBs — Nissan platforms sometimes have free dealer service options that shops miss.

Related Codes You May See With P1446

P0446
EVAP Vent Control (Toyota Camry) — direct generic sister code; same valve hardware with generic OBD-II detection; identical cleaning/replacement diagnostic approach
P0441
EVAP Incorrect Purge Flow — companion EVAP code; often co-occurs because vent valve issues affect purge diagnostics
P0455
EVAP Large Leak (Silverado) — common P1446 companion; vent valve unable to close causes false leak detection
P0460
Fuel Level Sensor (Ford F-150) — same fuel tank assembly diagnostic family; helpful diagnostic methodology for tank-mounted components
P0140
O2 Sensor No Activity Bank 1 Sensor 2 — same emissions monitoring system family; underbody connector corrosion patterns apply
P0130
O2 Sensor Circuit Bank 1 Sensor 1 — same OBD-II emissions monitoring methodology; resistance test diagnostic approach applies
P061B
Internal Control Module Torque (BMW 330i) — same ECM diagnostic methodology used for ECM reflash troubleshooting on P1446 rare cases

Frequently Asked Questions

Can I drive with a P1446 code?
Yes, generally safe to drive — but address before next emissions inspection. P1446 is moderate severity — primarily an emissions issue with limited driveability impact. Direct consequences: (1) Failed Emissions Test — vehicle will FAIL OBD-II emissions inspection until P1446 is cleared; the active CEL is automatic failure in most US states; this prevents registration renewal. (2) Strong Fuel Vapor Smell — particularly noticeable when refueling or in hot weather (fuel vapors escape through the unable-to-seal vent valve). (3) Difficulty Refueling — some vehicles have refueling problems because canister pressure can't equalize properly when vent valve is malfunctioning; pump may click off repeatedly. (4) Slight Fuel Economy Loss — 1-2 MPG; minor. (5) No Direct Engine Damage — the EVAP system is purely emissions-related; engine runs normally. Address P1446 within 1-2 months at most — there's no rush for engine protection, but you can't pass emissions inspection until it's fixed. Most repairs cost $0-$150 in parts depending on whether cleaning resolves the issue or replacement is needed.
Is P1446 different from P0446?
Yes — they're related but distinct. P0446 is a GENERIC OBD-II code applicable to all manufacturers — defined as 'EVAP System Vent Control Circuit Malfunction' (general electrical fault). P1446 is a MANUFACTURER-SPECIFIC code primarily used by Nissan/Infiniti (and occasionally VW/Audi on early 2000s models) — defined as 'EVAP Canister Vent Control Valve Close' (specific failure mode — valve can't close when commanded). Pattern recognition: P0446 indicates broader electrical/circuit issues affecting the vent valve area; P1446 specifically targets the valve's inability to seal closed for diagnostic leak testing. Diagnostic approach overlap: both benefit from resistance testing, visual inspection, and bidirectional activation; P1446 has additional Nissan-specific testing using Nissan-compatible scanner tools (like UR800). Same vent valve hardware on Nissan vehicles can trigger either P0446 (generic) OR P1446 (Nissan-specific) depending on the specific failure mode detected. Both codes ultimately require similar repair: clean valve, test electrically, replace if needed.
Why does the Nissan EVAP vent valve get stuck?
The Nissan EVAP canister vent valve sticks open from a combination of design and environmental factors. THE VALVE'S NORMAL FUNCTION: usually OPEN (allows fresh air into canister); ECM commands CLOSED only briefly during EVAP leak diagnostics (creates sealed system for pressure decay test). THE FAILURE MODES: (1) Dust Intrusion — the valve's fresh air intake draws ambient air through the canister vent; over 60,000-150,000 miles, dust accumulates on the plunger seat preventing complete seal; particularly common in dusty climates or on vehicles driven on unpaved roads. (2) Water Intrusion — Nissan canister mounting locations (under vehicle, near rear) expose the valve to road spray; water enters the fresh air intake, corrodes valve internals, and damages the cyclonic filter that Nissan engineers added specifically to prevent this. (3) Carbon Migration — fuel vapor carbon migrates from canister to valve over time; combined with dust, creates sticky deposits. (4) Spring Fatigue — the plunger return spring weakens after thousands of cycles; valve doesn't fully seat. The valve was redesigned multiple times during Nissan's 2005-2018 production years specifically to address these issues — newer Nissan vehicles have better dust/water protection.
How much does it cost to fix P1446?
Cost varies by root cause. Cleaning the existing valve (FIXES 25-30% of cases): $5-$10 in electrical contact cleaner + 15 minutes DIY; FREE if you have cleaner on hand. EVAP canister vent valve replacement (FIXES 40-50% of cases): $40-$150 OEM Nissan part + 30 minutes labor DIY ($150-$350 at shop). EVAP pressure sensor replacement (FIXES 15-20%): $50-$150 + 30 minutes DIY. Wiring repair / connector cleanup: $5-$30 DIY. EVAP canister replacement (water-saturated, 10-15%): $80-$250 + 1-2 hours labor DIY ($250-$500 at shop). Vacuum tube replacement: $10-$30. Most P1446 cases resolve under $200 DIY when proper diagnostic procedure is followed. Shop cost: $200-$500 typical. The biggest cost-saver: perform Step 3 cleaning ($5-$10) BEFORE accepting any replacement quote — about 25-30% of P1446 cases resolve completely with cleaning. The 15-minute time investment is dramatically cheaper than parts.
What scanner do I need to fix P1446?
P1446 diagnosis requires a scanner with bidirectional EVAP control + Nissan-specific data support. The iCarzone UR800 is at $299.99 — perfectly suited to P1446 diagnosis. Key features for P1446: bidirectional EVAP canister vent valve activation on Nissan/Infiniti platforms (commands valve ON/OFF for Step 4 verification — essential for confirming the valve responds mechanically to ECM commands); EVAP system pressure live data (verify pressure change when valve commanded closed — catches the 'clicks but doesn't seal' marginal failures); EVAP leak test routine on Nissan-compatible vehicles (helps identify whether P1446 has caused secondary EVAP leak codes like P0442); freeze frame data showing exact conditions when P1446 triggered (helps diagnose intermittent valves); broad Nissan/Infiniti coverage including Altima (2007-2018 — highest-volume P1446 platform), Maxima, Sentra, Frontier, Pathfinder, Murano, Rogue, Versa, Quest, and Infiniti G35/G37/M35/M37/EX/FX. The UR800's combination of Nissan-specific bidirectional EVAP + EVAP pressure monitoring is the killer feature combination for P1446 — without it, distinguishing cleanable contamination from full valve failure requires expensive guess-and-replace approach.
Why is P1446 common on older Nissan models?
Nissan Altima/Maxima 2005-2015 and Infiniti G35/G37 are the highest-volume P1446 platforms for both design and aging reasons. DESIGN FACTORS: the early-generation Nissan EVAP canister vent valve had a more open intake design than later models; this allowed more dust/water intrusion. Nissan engineers redesigned the valve multiple times during 2007-2015 production specifically to improve dust/water protection. AGING FACTORS: at 100,000-150,000 miles (when many Nissan vehicles of this era are now), accumulated dust/contamination reaches the threshold where valve fails to seat. NISSAN MOUNTING: the canister and vent valve on these platforms are mounted in the wheel well or under rear of vehicle — exposed locations that receive significant road spray. CYCLONIC FILTER: Nissan added a 'cyclonic filter' to the valve fresh air intake on later models specifically to address P1446 patterns; vehicles without this filter (early-mid 2000s) are more prone to the failure. The diagnostic implication: Nissan/Infiniti vehicles 2005-2015 with 100,000+ miles benefit MOST from the Step 3 cleaning procedure; about 40-50% of these vehicles' P1446 codes respond to thorough cleaning.
Why won't the gas pump click off properly?
If your Nissan with P1446 has trouble refueling (pump clicks off repeatedly even when tank isn't full), the EVAP canister vent valve stuck closed is a common cause. The mechanism: during normal refueling, fuel displaces air in the tank; this air must escape somewhere; the EVAP system routes the displaced air through the canister (carbon absorbs fuel vapor) and out the vent valve (which is normally OPEN). If the vent valve is stuck CLOSED (P1446 inverse — actually P1444 territory) OR if the valve mechanism is partially failed, displaced air can't escape; tank pressurizes; gas pump nozzle senses backpressure and clicks off as if tank is full. Distinctive pattern: Nissan with P1446 + refueling difficulty + works fine with slow pump speeds; problem dramatically worse on hot days (additional vapor pressure). The fix is the same as base P1446 diagnosis — clean or replace the vent valve. Note: although P1446 specifically indicates 'can't close,' a fully failed valve sometimes presents with mixed symptoms (refueling problems suggest 'stuck closed' but code reads 'can't close'); both directions of failure on the same valve are possible at advanced wear stages.
Will P1446 cause damage if I ignore it?
Minimal direct engine damage — but indirect consequences accumulate. DIRECT MECHANICAL IMPACT of ignoring P1446: essentially NONE for the engine itself; the EVAP system operates only during specific diagnostic cycles and refueling; the engine runs normally with or without working vent valve. INDIRECT CONSEQUENCES: (1) Failed Emissions Tests — most US states require OBD-II emissions inspection for registration renewal; active CEL or stored P1446 fails the test; you cannot legally re-register the vehicle until cleared. (2) Strong Fuel Vapor Odor — particularly noticeable when refueling, in hot weather, or in enclosed spaces (garage); not pleasant for vehicle occupants or environment. (3) Refueling Difficulty — pump click-off problems make filling tank frustrating. (4) Secondary EVAP Codes — P1446 prevents proper EVAP leak diagnostics; over time, secondary codes (P0442 small leak, P0455 large leak) may accumulate even if no actual leak exists; these can be misdiagnosed as separate issues. (5) Possible Increased Hydrocarbon Emissions — minor environmental impact from improperly retained fuel vapors. NOT typically a long-term engine damage risk like P0741 transmission or P0306 misfire codes. Address P1446 within 1-2 months when convenient; no need for emergency repair, but don't ignore for years.
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Our team of ASE-certified technicians and OBD-II diagnostic engineers review every article for technical accuracy. Content is based on hands-on diagnostic experience across domestic, Asian, and European vehicle platforms.

10+ years diagnostic experience ASE Certified Last reviewed: June 2026