P0571 Code: The $15 Brake Switch Fix Most Shops Miss

P0571 Code: The $15 Brake Switch Fix Most Shops Miss

STOP — Don't Pay $200 for Diagnostics Yet. Watch Your Brake Lights First — That 30-Second Test Solves Most P0571 Cases.

P0571 Code: The $15 Brake Switch Fix Most Shops Miss

P0571 is one of the easiest and cheapest OBD-II codes to fix — but only if you know the secret. The Check Engine Light comes on, cruise control stops working, brake lights act strange, and the shift lever may lock in Park. Most owners pay $150-$200 at a shop for "diagnostics" that ends with a $15 brake light switch replacement. The truth: a free 30-second brake light visual test tells you the answer before you spend a penny. About 50-60% of P0571 cases are a $10-$30 brake switch you can replace yourself in 20 minutes. This guide shows the simple test most shops skip.

Updated June 2026 7 min read DIY Difficulty: Beginner Fix Cost: $1 – $200
⚡ QUICK ANSWER

P0571 means "Cruise Control / Brake Switch 'A' Circuit Malfunction" — the PCM detected the brake light switch isn't operating within expected parameters. The brake light switch is a small electrical switch mounted on the brake pedal bracket; pressing the pedal closes the circuit and sends a signal to three different systems: brake lights, cruise control deactivation, and shift interlock release. When the switch fails or its circuit is broken, all three systems are affected simultaneously. Cause distribution: about 50-60% are a failed brake light switch ($10-$30 replacement), 15-20% are loose or corroded connector ($5-$30), 10-15% are blown stop lamp fuse ($1-$5), 5-10% are switch misalignment / loose mounting ($0 adjustment), 5-10% are wiring damage, and under 5% are PCM hardware failure. Diagnostic priority: watch the brake lights FIRST — this free 30-second test reveals the answer in most cases.

What Does P0571 Actually Mean?

The brake light switch is a deceptively important component. Mounted on the brake pedal bracket, it's a simple two-state electrical switch: open when the pedal is at rest, closed when the pedal is pressed (or reverse on some designs — both wiring patterns exist). But that simple ON/OFF signal feeds at least three critical systems: brake lights (telling drivers behind you that you're stopping), cruise control (must disengage when you brake), and shift interlock (you can only shift out of Park with brake pressed). On modern vehicles, the same signal also feeds stability control (ESC), ABS calibration, and hybrid regenerative braking systems.

P0571 fires when the PCM detects this signal is misbehaving — either always-on (switch stuck closed), always-off (switch stuck open), or erratic/intermittent. The 'A' in "Brake Switch A" refers to the primary brake light switch circuit. Some platforms have a secondary 'B' switch for redundancy or specifically for cruise control deactivation (these set P0573, P0703, or P0504 codes instead). The fault almost always traces to the physical switch on the pedal bracket — making P0571 one of the simplest and cheapest OBD-II codes to diagnose and repair correctly.

P0571 vs other brake switch codes — when the codes differ: P0571 = Brake Switch A Circuit Malfunction (this article — generic circuit fault). P0572 = Brake Switch A Circuit Low (signal stuck near 0V — usually open circuit or unplugged switch). P0573 = Brake Switch A Circuit High (signal stuck near 5V — usually short to power). P0574 = Cruise Control System - Vehicle Speed Too High. P0703 = Brake Switch B Circuit. P0504 = Brake Switch A/B Correlation (2-switch design mismatch). All brake switch codes share the same diagnostic approach: watch brake lights first, then check fuse, then test switch with multimeter.
Critical — never authorize PCM replacement on P0571 without documented brake switch test: P0571 is so commonly a $15 brake switch that ASE-certified shops should ALWAYS test the switch before suggesting any expensive repair. If a shop quotes $800+ for "PCM replacement" or even $300+ for "diagnostic and wiring repair" without first documenting brake light switch testing, get a second opinion immediately. The brake light test takes 30 seconds; switch multimeter test takes 5 minutes. There's no legitimate reason to skip these. Shops that jump to PCM diagnosis on P0571 are either uninformed or aggressively padding the bill.

What Are the Symptoms of P0571?

P0571 symptoms are unusually clear and consistent because the brake switch affects multiple specific systems:

Check Engine Light — always; sometimes the only obvious sign
Cruise control won't set — most common driveability symptom
Cruise control fails to disengage — safety concern; brake must override
Brake lights stuck ON — switch closed permanently; drains battery
Brake lights NEVER come on — switch stuck open; rear-end collision risk
Brake lights flickering — intermittent contact in switch
Shift lever stuck in Park — shift interlock won't release
Stability control / ABS warnings — modern systems use the same signal
The "can't get out of park" diagnostic tell: If you sit in your vehicle, press the brake pedal, and the shift lever still won't move from Park to Drive — combined with P0571 — that's the textbook brake switch failure symptom. The shift interlock solenoid needs a "brake pedal pressed" signal to release the lever; without that signal, the lever stays locked. Most vehicles have a manual override called "Shift Lock Release" — a small button near the gear lever (sometimes hidden under a removable plastic cap). Press and hold this button while pressing the brake to manually release the lever. This gets you to a repair location — but the brake switch must still be repaired.

Is P0571 Code Serious?

Moderate to high severity — depends on which symptom you have. Address within days, not weeks.

Brake lights stuck OFF → SERIOUS rear-end collision risk
Brake lights stuck ON → battery drain + driver confusion
Cruise control fails only → annoyance, not danger
Shift interlock locked → can't drive at all (use release button)
Diagnostic misdiagnosis risk → HIGH; overpaying for shop diagnostics when 30-second test reveals answer

The defining feature of P0571: the actual fix is one of the cheapest in OBD-II, but uninformed owners or aggressive shops can turn it into a $200-$500 bill. The expensive misdiagnosis pattern: P0571 → owner takes to shop → shop charges $120-$200 diagnostic fee → tells owner "wiring issue, $400 to repair" → owner pays $600 total when a $15 brake switch and 20 minutes would have fixed it. The cheap fix pattern: P0571 → owner watches brake lights → notices they don't come on → checks fuse first ($3) or buys new OEM brake switch ($25) → installs in 20 minutes → drives away. Knowing this code is the single best money-saver in the OBD-II catalog.

Severity rating: 🟠 Moderate to high. Brake lights stuck OFF is genuinely dangerous — drivers behind you can't see when you're braking, creating rear-end collision risk especially at night. Address immediately. Brake lights stuck ON is less acute but drains your battery overnight and other drivers may not realize when you're actually braking. Cruise control failure alone is a minor annoyance. Either way, the fix is cheap — usually under $50 — so there's no good reason to delay. Most P0571 cases resolve in 30 minutes of DIY time and $30 in parts.

What Causes a P0571 Code? (Ranked by Frequency)

Cause distribution heavily favors the brake light switch itself because that's the simplest failure point in the circuit:

1

Failed Brake Light Switch (50-60% of Cases)

The dominant P0571 cause. The brake light switch is mechanically actuated thousands of times per drive cycle — every time you press and release the brake pedal. Internal contacts wear, springs weaken, plastic plunger deforms. After 80,000-150,000 miles, switch failure is statistically inevitable. Symptoms: P0571 plus one of the specific brake light behaviors (always on, never on, flickering). Identification: simply watch your brake lights (Step 2). Fix: OEM brake light switch replacement ($10-$30) in 15-20 minutes DIY. About 50-60% of P0571 cases stop here. The cheapest OBD-II fix in the catalog.

Fix: $10–$30 OEM brake switch
2

Loose or Corroded Connector (15-20%)

The brake switch electrical connector sits in the footwell area — exposed to dust, occasional moisture from wet shoes, and continuous vibration from pedal use. Connector pins corrode (green sulfate), insulation hardens, retaining clip weakens allowing wiggling. Distinctive: intermittent P0571 — code returns then clears spontaneously; wiggling connector changes the brake light state. Fix: disconnect connector; clean terminals with electrical contact cleaner; apply dielectric grease; reconnect firmly ($5-$15 total). About 15-20% of P0571 cases.

Fix: $5–$30 connector cleanup
3

Blown Stop Lamp Fuse (10-15%)

The simplest possible cause — and most often overlooked. The brake light circuit is protected by a fuse (typically 10A or 15A) labeled "STOP LAMP" or similar. If a brake light bulb shorts internally, the fuse blows to protect the wiring. Distinctive: brake lights NEVER come on (not even slightly); P0571 set immediately. Fix: locate fuse box (usually under hood), find STOP LAMP fuse, replace with same amperage ($1-$5). If new fuse blows immediately, there's a short circuit downstream — replace shorted bulb first. About 10-15% of P0571 cases. The free first check before any other diagnosis.

Fix: $1–$5 new fuse
4

Brake Switch Misalignment / Loose Mounting (5-10%)

The brake switch must be installed at exactly the right thread depth or pin position so its plunger contacts the pedal arm correctly. If the switch loosens over time (vibration), or a previous repair installed it incorrectly, the contact timing is wrong — switch may trigger too early, too late, or not at all. Distinctive: P0571 after recent brake work; switch is physically loose when you try to wiggle it; lights work intermittently with strange pedal positions. Fix: adjust switch position (typically a 1/4 turn at a time) until brake lights respond correctly to pedal travel. $0 if switch itself is good.

Fix: $0 adjustment
5

Damaged Wiring (5-10%)

Wiring from brake switch to PCM runs through the dash area. Common failure points: chafing against metal brackets, rodent damage (mice love wire insulation in winter), heat damage from nearby components, broken wire from collision repair. Distinctive: intermittent P0571 that worsens with vibration; multimeter test shows broken continuity in specific harness section. Fix: trace wire, locate break, splice with high-temp wire ($15-$30) or replace harness section.

Fix: $15–$60 wiring repair
6

Brake Pedal Arm Bushing Wear (3-5%)

Common on older vehicles (150,000+ miles). The pedal arm pivot bushing wears, allowing the pedal arm to sit at a slightly different angle than designed. This changes the relationship between pedal position and switch plunger position — switch may not return fully, or may not extend fully when pressed. Distinctive: P0571 on high-mileage vehicle; pedal feels "loose" or wobbly at the pivot; replacing brake switch alone doesn't fix the problem. Fix: replace pedal arm bushing ($10-$30 part + 1-2 hours labor).

Fix: $10–$150 bushing replacement
7

Wrong Brake Light Bulb Installed (1-2%)

An unusual but documented cause. Some modern vehicles monitor the brake light bulb current draw — if the wrong wattage bulb is installed (too low for the circuit), the PCM sees abnormal current flow and sets P0571 plus other related codes. Common after DIY brake light bulb replacement using LED bulbs without proper resistors. Distinctive: P0571 appeared after brake light bulb change; bulbs are LED upgrades. Fix: install correct OEM-spec bulbs OR add proper load resistors for LED upgrades.

Fix: $10–$40 correct bulbs
8

PCM Hardware Failure (Very Rare, <5%)

PCM internal circuit failure misinterpreting brake switch signals. Extraordinarily rare on P0571. Should be considered ONLY after all other causes (switch, fuse, wiring, connector) are confirmed good. Fix: PCM replacement + programming ($800-$1,500); see P0685 article for PCM diagnostic approach.

Fix: $800–$1,500 PCM

What You'll Need

Tools

  • OBD2 scanner with live brake switch data iCarzone UR800 ›
  • Digital multimeter (continuity + DC voltage)
  • Helper to watch brake lights (or phone camera against garage door)
  • Basic socket set + screwdrivers
  • Flashlight (brake switch is in dark footwell area)
  • Fuse puller (or needle-nose pliers)

Possible Parts & Supplies

  • OEM brake light switch $10–$30
  • Replacement stop lamp fuse (10A or 15A) $1–$5
  • Electrical contact cleaner $5–$8
  • Dielectric grease for connector $5–$10
  • Brake pedal arm bushing (if worn) $10–$30
  • OEM brake light bulbs (if wrong type installed) $10–$30
Recommended Diagnostic Tool for P0571

iCarzone UR800 — 5" LCD OBD2 Diagnostic Scanner

★★★★★ Live Brake Switch Data · Quad-Core · Wi-Fi

5-inch LCD diagnostic scanner with quad-core 1.3GHz processor — perfect for P0571 diagnosis without paying for premium features you don't need. Live data display includes brake switch input voltage in real time — you can press the pedal and watch the signal change instantly from 0V to 5V (or whatever your platform uses), confirming switch operation. Freeze frame data review shows exactly when the code triggered. Broad platform coverage includes VW/Audi (very common P0571 platform — A4/Q5 brake switch documented failure), Ford F-150 / Mustang (Motorcraft switch), Toyota Camry / Tacoma, Honda Civic / Accord, Chevrolet Silverado / Tahoe, BMW 3/5 Series, Mercedes-Benz E/C, and most European/Asian platforms. The UR800 reads, displays, and clears P0571 plus virtually all OBD-II codes you'll encounter — without the premium price.

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How Do You Fix a P0571 Code?

Follow these steps in order. Step 2 (free brake light visual test) is the killer diagnostic — it resolves about 50-60% of cases for $0 in 30 seconds.

P0571 Diagnostic Flowchart — Decision Tree

P0571 Diagnostic Flowchart Decision tree starting with scan codes and note symptoms, the free 30-second brake light visual test, stop lamp fuse check, brake switch visual inspection, multimeter switch test, and switch replacement as the final step. START · Scan codes + symptoms Step 2: WATCH THE BRAKE LIGHTS FREE 30-second test — does the work Stuck on? Never on? Flickering? DIAGNOSED! $15-30 switch Step 3: Check stop lamp fuse $1-5 fuse — free first check Step 4: Locate + inspect switch Under footwell, brake pedal bracket Step 5: Multimeter test switch Continuity changes when pedal pressed Step 6: Replace OEM switch 15-20 min DIY · $10-30 part Adjust + verify brake lights
Figure 1: P0571 diagnostic decision tree — Step 2 (watching brake lights) is the killer diagnostic. About 50-60% of cases resolve for $15-30 in 20 minutes total. The cheapest OBD-II repair in the catalog.
  • 1

    Scan All Codes and Note Symptoms

    Plug in scanner, record all codes. P0571 is in the brake switch family — record companion codes:

    • P0571 — Cruise Control / Brake Switch A Circuit (this article — generic circuit fault)
    • P0572 — Brake Switch A Circuit Low (signal stuck near 0V)
    • P0573 — Brake Switch A Circuit High (signal stuck near 5V)
    • P0574 — Cruise Control - Vehicle Speed Too High
    • P0703 — Brake Switch B Circuit (secondary switch fault)
    • P0504 — Brake Switch A/B Correlation (2-switch mismatch)

    Note actual symptoms — these tell you which failure mode:

    • Cruise control won't enable / set / resume?
    • Brake lights stuck ON when engine running?
    • Brake lights NEVER come on when pressing pedal?
    • Brake lights flickering as pedal moves?
    • Shift lever stuck in Park (can't move to Drive)?
    • Stability control / ABS warning lights also on?

    Symptom patterns:

    • Brake lights always ON = switch stuck closed → replace switch (Step 6)
    • Brake lights NEVER on = switch stuck open OR blown fuse → check fuse first (Step 3)
    • Brake lights flickering = intermittent contact → replace switch
    • Shift lever locked + all above = same brake switch is the cause
  • 2

    Watch the Brake Lights — The Free 30-Second Diagnostic

    The single most diagnostic step on P0571. Most shops skip this and charge $120-$200 for a multimeter diagnosis when 30 seconds of observation reveals the answer:

    Setup options:

    • With a helper: have them stand behind the vehicle while you sit in driver's seat
    • Solo with garage: back up to garage door; brake lights reflect off door visible in mirrors
    • Solo with phone: set phone camera behind vehicle in video mode; play back later
    • Solo at night: brake lights reflect off any reflective surface near vehicle

    Test procedure:

    • Turn key to ON position (engine doesn't need to start)
    • Foot OFF brake pedal entirely — observe brake lights
    • Are brake lights ON when pedal is NOT pressed? → YES = switch STUCK CLOSED; replace switch (skip to Step 6)
    • Now press brake pedal slowly
    • Do brake lights turn ON immediately as pedal moves? → NO = switch STUCK OPEN or BLOWN FUSE (continue to Step 3)
    • Hold brake pedal pressed
    • Are brake lights STEADY ON? → flickering = intermittent contact; replace switch
    • Release brake pedal
    • Do brake lights turn OFF immediately? → NO = switch sticky; replace switch
    • Press pedal partway (about half travel) — brake lights should turn ON well before reaching the floor

    Decision tree summary:

    • Brake lights behave abnormally = brake switch is the problem → Step 6 (replace switch)
    • Brake lights NEVER come on (not even one bulb) = check fuse first → Step 3
    • Brake lights behave normally = something else triggered P0571 → continue Step 4-5 (rare; less than 30% of cases)
    This 30-second test is the most important P0571 diagnostic step. About 70-80% of P0571 cases can be definitively diagnosed at this point — without any tools, fees, or shop visits. Most owners who pay $200+ at shops never had this simple test done.
  • 3

    Check the Stop Lamp Fuse

    If brake lights don't come on at all in Step 2, check the fuse before assuming switch failure:

    Locating fuse boxes:

    • Most vehicles have TWO fuse boxes: under hood (engine bay) AND in interior
    • Interior fuse box locations:
      • Under dash on driver's side (most common)
      • Inside glove box (especially Asian platforms)
      • Beside driver kick panel
      • Behind a removable plastic panel on driver side door jamb
    • Brake light / stop lamp fuse is usually in the INTERIOR fuse box

    Identifying the fuse:

    • Owner's manual has fuse diagram showing each fuse's purpose
    • Look for: "STOP LAMP", "BRAKE", "BRK LMP", "BRK SW" — labels vary
    • Typical amperage: 10A or 15A (color-coded: 10A = red, 15A = blue)

    Testing the fuse:

    • Pull fuse with fuse puller tool (built into many fuse box covers) or needle-nose pliers
    • Visual test: hold fuse up to light; internal metal strip should be intact and continuous; broken or visibly burned strip = blown fuse
    • Multimeter test (definitive): continuity setting; touch probes to each metal blade; should beep (continuity) — silence = blown fuse

    Replacement:

    • Use SAME amperage rating ONLY (color must match)
    • NEVER substitute higher amperage — can cause wiring overheat / fire
    • New fuses: $1-$5 at any auto parts store or hardware store

    If new fuse blows immediately: there's a short circuit somewhere in the brake light wiring. Common culprits: a brake light bulb with internal short; damaged wire grounding to chassis; wrong-spec LED bulb conversion. Replace any obviously bad bulbs first.

    About 10-15% of P0571 cases stop here with $3 fuse replacement.

  • 4

    Locate and Inspect the Brake Light Switch

    If fuse is OK and brake lights behave abnormally, locate the switch for inspection:

    Brake switch location:

    • Mounted on the brake pedal bracket in the driver's footwell
    • The bracket holds the brake pedal arm; switch is on the bracket where the pedal arm contacts when released
    • You'll need to be on your back on the driver's seat or kneeling in the footwell, looking UP and FORWARD
    • Flashlight essential — the area is dark

    Switch identification:

    • Small cylindrical part, usually black or white plastic
    • Threaded or pin-mounted into the bracket
    • Has a small spring-loaded plunger that the brake pedal arm contacts
    • Electrical connector with 2-4 wires
    • About thumb-sized on most vehicles

    Multi-switch designs (Mazda, BMW, some VW): some platforms have TWO switches on the same brake pedal bracket:

    • One for brake lights (the "A" switch — primary)
    • One for cruise control deactivation (TCC brake switch, the "B" switch)
    • Different colored wires distinguish them — service manual specifies exact wire colors
    • P0571 specifically targets the "A" switch (primary)

    Visual inspection:

    • Cracked or broken plastic body?
    • Bent or stuck plunger?
    • Loose mounting — switch wiggles in the bracket?
    • Connector damaged, oil-contaminated, loose pins?
    • Plunger position: should be slightly DEPRESSED when pedal is at rest; fully EXTENDED when pedal is pressed (or reverse on some normally-closed designs)

    Wiggle test: with engine running and helper watching brake lights, gently wiggle the switch body and connector. Brake lights flickering during wiggle = intermittent contact confirmed.

  • 5

    Multimeter Test the Brake Light Switch

    If visual inspection didn't reveal obvious failure, multimeter test:

    Procedure (basic continuity test):

    • Disconnect electrical connector from switch
    • Multimeter on CONTINUITY setting (beeper)
    • Place probes on the two switch terminals (some switches have 4 terminals; test pairs based on wire color or service manual)
    • Pedal RELEASED (plunger pressed in by pedal arm): test continuity
      • Most modern designs: NO continuity (no beep) when released — normally-open
      • Some older designs: continuity (beep) when released — normally-closed
    • Pedal PRESSED (plunger extended): test continuity again
      • Should switch state — opposite of what it was when released
    • Repeat 5-10 times rapidly pressing and releasing — switch should reliably change state every cycle
    • Intermittent state changes = failed switch; replace
    • Same state in both positions = stuck switch; replace

    Resistance test (more thorough):

    • Multimeter on OHMS (Ω) setting, lowest range
    • Test same probe positions
    • Closed circuit should read 0-1 ohm (essentially zero)
    • Open circuit should read infinity / OL (over limit)
    • If closed circuit reads 50+ ohms, internal contacts are corroded — replace switch even if continuity beeps

    Wiring side test:

    • Reconnect connector to switch
    • Key ON, engine OFF
    • Multimeter on DC volts; ground probe to chassis
    • Test signal wire probe at connector — should read 0V or 5V depending on platform (consult wiring diagram)
    • Missing reference voltage = wiring or PCM issue (rare)
  • 6

    Replace the Brake Light Switch — The Final Fix

    Most P0571 cases end here with $10-$30 switch replacement. One of the easier OBD-II repairs:

    Choosing replacement switch:

    • OEM strongly recommended:
      • Ford / Lincoln — Motorcraft
      • GM (Chevy / Buick / Cadillac / GMC) — AC Delco (Chevy Silverado specific: P/N 15109338 with retainer 10418918)
      • Chrysler / Dodge / Jeep / Ram — Mopar
      • Toyota / Lexus — Toyota Genuine (Denso)
      • Honda / Acura — Honda Genuine
      • VW / Audi — VAG (P/N 8E0 945 511 series widely available)
      • BMW — Genuine BMW
    • Verify part number matches your VIN — many vehicles have multiple brake switch variants by year/model
    • Aftermarket switches have higher failure-from-new rates; the $5-$15 cost saving isn't worth the repeat repair

    Installation procedure:

    • Engine OFF, key out, parking brake set
    • Disconnect old switch electrical connector (squeeze release tab)
    • Most switches thread out — turn counterclockwise to remove
    • Some use a locking clip or pin — push tab while pulling switch
    • Note exact thread depth or pin position — new switch must install to same depth
    • Install new switch — thread in (or pin in) until plunger lightly contacts pedal arm with pedal at rest
    • CRITICAL — proper adjustment:
      • Plunger should be depressed about 1-3mm when pedal is at rest
      • Plunger should be fully extended when pedal is pressed
      • If installed too shallow: pedal needs significant travel before lights come on
      • If installed too deep: plunger never extends fully; brake lights stuck ON
      • Adjust 1/4 turn at a time until correct
    • Reconnect electrical connector firmly
    • Test brake lights — OFF at rest, ON immediately when pedal pressed
    • Clear codes with scanner
    • Drive 5-10 miles through varied conditions to verify P0571 doesn't return
    If P0571 returns within days of new switch installation, the most common reason is incorrect adjustment. Adjust the threading 1/4 turn at a time — usually outward (less thread engagement) to give the plunger more travel. Second most common reason: aftermarket switch with wrong plunger length — return and exchange for OEM.

How Much Does P0571 Cost to Fix?

P0571 is one of the cheapest OBD-II codes — about 75% of cases resolve under $30. The biggest cost saving is doing the diagnosis yourself instead of paying a shop's $120-$200 diagnostic fee.

Repair DIY Cost Shop Cost You Save Type
Diagnostic — brake light visual test $0 $120–$200 Up to $200 30-Sec Free Test
Stop lamp fuse replacement $1–$5 $30–$80 Up to $75 DIY Trivial
OEM brake light switch (fixes 50-60% of cases) $10–$30 $80–$200 Up to $170 15-Min Fix
Connector cleanup + dielectric grease $5–$15 $60–$120 Up to $105 DIY Easy
Switch adjustment (if misaligned only) $0 $50–$100 Up to $100 $0 Adjustment
Wiring splice + heat protection $15–$30 $120–$250 Up to $235 DIY Moderate
Brake pedal arm bushing replacement $10–$30 part $100–$300 Up to $270 DIY Moderate
Correct OEM brake bulbs (LED upgrade gone wrong) $10–$40 $50–$100 Up to $60 DIY Easy
PCM replacement (extraordinarily rare) N/A $800–$1,500 — Last Resort
The diagnostic ROI: The $299 UR800 scanner with live brake switch data pays for itself on this single P0571 case — saving $200 in shop diagnostic fees that aren't needed when you have your own scanner. Plus the scanner reads codes, displays freeze frame, and clears codes for virtually all OBD-II issues you'll see over the years. For most home DIYers, the UR800 is the right scanner choice — full diagnostic capability without paying for premium features (like advanced bidirectional or PCM reflash) that are rarely needed for basic OBD-II repairs. After 2-3 home repairs, the scanner has paid for itself many times.

Per the EPA's emissions standards ↗ EPA Vehicle Emissions I/M Program, a vehicle with an active P0571 code will fail OBD-II emissions inspection. The brake light switch isn't typically considered an emission component but the active code prevents readiness monitors from completing. Some powertrain components related to this code are covered under federal emissions warranty for the first 8 years / 80,000 miles. Verify with your dealer using VIN before paying out of pocket on newer vehicles.

Which Vehicles Are Most Prone to P0571?

P0571 appears on virtually any OBD-II vehicle (1996+ in USA) with electronic cruise control or automatic transmission shift interlock. High-volume platforms: VW/Audi (very common — well-documented switch failure) and Ford F-150 (high-mileage Motorcraft switch failures). Deep-dives below.

Make Model / Platform Years Primary Cause & Notes Risk
Volkswagen / Audi Jetta, Golf, Passat, Tiguan / A3, A4, A6, Q5 2005–2024 VAG brake switch P/N 8E0 945 511 series — well-documented failure. See VW/Audi deep-dive. High
Ford / Lincoln F-150, Mustang, Escape, Focus, Lincoln MKX 2003–2024 Motorcraft switch typically lasts 80,000-150,000 miles. See Ford deep-dive. High
Toyota / Lexus Camry, Tacoma, Corolla, Highlander, Lexus RX/ES 2005–2024 Denso brake switch — generally reliable but can fail at 130,000+ miles. Medium
Honda / Acura Civic, Accord, CR-V, Pilot, Acura MDX/TLX 2003–2024 Honda Genuine recommended; aftermarket has documented failures. Medium
Chevrolet / GMC / Cadillac Silverado, Tahoe, Suburban, Sierra, CTS, Escalade 2003–2024 AC Delco switch P/N 15109338 with retainer 10418918 — common service replacement. Medium
BMW / Mini 3 Series, 5 Series, X3, X5, Mini Cooper 2005–2024 Documented brake switch failures at 100,000+ miles. Medium
Mercedes-Benz C-Class, E-Class, S-Class, GLC, GLE 2005–2024 High-mileage switch failures common; multi-switch design on some models. Medium
Chrysler / Dodge / Jeep / Ram Cherokee, Wrangler, Grand Cherokee, Ram, Charger 2005–2024 Mopar brake switch — generally reliable; failures at high mileage. Low

P0571 on VW / Audi (Documented Brake Switch Failures)

VW Jetta/Golf/Passat/Tiguan and Audi A3/A4/A6/Q5 share the same VAG (Volkswagen Auto Group) brake switch design — one of the most documented P0571 platforms in North America:

1. VAG brake switch P/N 8E0 945 511 series (the famous one). VW and Audi vehicles 2005-2016 used a specific brake switch part number (variants 8E0 945 511 A through K) that has documented high failure rates. Internal contact wear typically occurs at 60,000-100,000 miles. Symptoms: P0571 + cruise control disabled + brake lights may work intermittently + shift lever sometimes locks in Park. Fix: replace with OEM VAG switch ($25-$40); aftermarket variants exist but VAG OEM is recommended. Installation takes about 15 minutes once you locate the switch under the dash near the brake pedal bracket. The replacement is a press-fit / clip-in design on most VAG vehicles (not threaded).

2. Newer VAG platforms (2017+) revised design. Volkswagen and Audi updated the brake switch design starting around 2017. The newer switches have better internal contacts and lower failure rates, but the failure mode remains the same — when they do fail at higher mileage (150,000+), it's still a $25-$40 fix.

3. VW/Audi multi-switch designs. Some VAG platforms use TWO brake switches on the pedal bracket — primary brake light switch + cruise/TCC deactivation switch. When P0571 sets specifically (not P0573 or P0703), the primary switch is the target. Service manuals confirm exact wire colors for each switch on each platform.

VW/Audi action plan: Step 2 brake light test first to confirm. Order VAG OEM brake switch ($25-$40) — verify exact part number using VIN at dealer parts counter or OEM-only online supplier. Replacement is press-fit / clip-in design (not threaded); takes about 15 minutes once located. NEVER buy generic aftermarket — VAG brake switches have documented compatibility issues with generic replacements. Plan $30-$50 total cost for most VW/Audi P0571 cases.

P0571 on Ford F-150 / Mustang / Escape (Motorcraft Switch)

Ford F-150, Mustang, Escape, and other Ford/Lincoln platforms use Motorcraft brake switches — generally durable but eventually fail at high mileage:

1. Motorcraft brake switch high-mileage failure. Ford brake switches typically last 80,000-150,000 miles before showing wear. Symptoms: P0571 + cruise control intermittent + brake lights may flicker before complete failure. Distinctive on F-150: brake lights may behave normally while cruise control fails — Ford uses redundant switching that masks the early failure signs. Fix: Motorcraft brake light switch (varies by F-150 generation — typical part numbers BL3Z-13480-A series for 2015-2020). $20-$35 OEM.

2. F-150 brake pedal arm bushing wear (high-mileage). On F-150 trucks with 180,000+ miles, the brake pedal arm pivot bushing wears, allowing pedal arm to sit slightly off-angle. Even a new brake switch doesn't fully resolve P0571 because the pedal-to-switch geometry is wrong. Fix: replace bushing first ($15-$30), then brake switch if still failing.

3. Mustang brake switch on track-driven vehicles. Mustang Mach 1, GT350, and GT500 driven on track see accelerated brake switch wear due to high-frequency pedal use during braking events. Symptoms: P0571 on Mustang with track miles even at lower total mileage. Fix: same Motorcraft brake switch replacement; consider higher-spec aftermarket racing switch for track-only vehicles.

Ford action plan: Step 2 brake light test first. Motorcraft OEM brake switch ($20-$35) — verify exact part number using VIN. F-150 specifically: also inspect brake pedal arm bushing if vehicle has 180,000+ miles. Replacement is threaded design on most Ford platforms (not clip-in); install plunger slightly depressed at rest, fully extended when pedal pressed. Plan $25-$50 total cost for most Ford P0571 cases.
How to check for a TSB: Visit NHTSA.gov ↗, enter your VIN. Search for "P0571," "brake switch," "stop lamp switch," or "cruise control" + your specific platform name. P0571 is sometimes covered under federal emissions warranty (the brake switch itself isn't an emission component, but the cruise control system may qualify on some platforms). Some platforms have extended warranty coverage worth $100-$300.

Should You DIY or Call a Mechanic?

DIY If You…
  • ✓ Can use a multimeter (continuity beep test)
  • ✓ Can locate your fuse box (driver footwell / under dash)
  • ✓ Are comfortable kneeling/lying in driver's footwell area
  • ✓ Have basic socket set and screwdrivers
  • ✓ Own OBD2 scanner for clearing codes
  • ✓ Want to save $100-$200 on shop diagnostic fees
Use a Mechanic If…
  • → Brake light switch test inconclusive after multiple attempts
  • → Wiring damage suspected (intermittent code returns)
  • → Multiple brake-related codes set simultaneously (system issue)
  • → Brake pedal arm bushing replacement needed (more involved)
  • → Vehicle still under powertrain warranty (free repair possible)
  • → Limited mobility prevents driver's footwell access
Never authorize PCM replacement or extensive diagnostic work on P0571 without documented brake switch test results. P0571 is so commonly a $15-$30 brake switch that any shop quoting PCM-level diagnostics or repair is either uninformed or padding the bill. Required from any shop before parts replacement over $100: documented brake light visual test results, multimeter test of brake switch (with/without pedal pressed), wiring continuity test results. If "we replaced the PCM" or "extensive wiring repair" is the diagnosis without brake switch testing, you may have overpaid by $300-$1,400. The brake switch test takes 5 minutes; visual test takes 30 seconds. Get a second opinion before authorizing any expensive work.

Related Codes You May See With P0571

P2138
APP/TPS voltage mismatch — same pedal sensor electrical circuit diagnostic methodology
P0685
ECM/PCM Power Relay Control Circuit — same PCM electrical circuit + fuse/relay diagnosis
P0120
Chevy Silverado TPS Circuit — same PCM input switch/sensor circuit diagnostic methodology
P0335
Crankshaft Position Sensor — same PCM input circuit diagnostic approach
P0121
Ford F-150 EcoBoost TPS Range/Performance — same PCM input circuit diagnostic methodology
P0572
Brake Switch A Circuit Low — sister code (signal stuck near 0V; generic reference)
P0573
Brake Switch A Circuit High — sister code (signal stuck near 5V; generic reference)

Frequently Asked Questions

Can I drive with a P0571 code?
Limited safe driving only. P0571 disables cruise control (annoying but not dangerous) AND can disable brake lights (very dangerous — drivers behind you don't see you stopping) AND can lock the shift interlock (you may not be able to shift out of Park to drive anywhere). Safety risk depends on which symptom you have: brake lights stuck OFF is a serious rear-end collision risk — repair immediately; brake lights stuck ON drains battery and confuses other drivers — repair within days; shift interlock locked means you can't drive at all (use shift release button or have vehicle towed). Most modern vehicles have a brake shift release button near the gear lever as backup to manually override Park. If brake lights work normally but only cruise control is affected, driving is safe — repair within a week.
Why won't my shift lever come out of Park?
Most modern automatic transmissions use a 'shift interlock' that mechanically blocks the shift lever from leaving Park unless the brake pedal is pressed. When the brake switch fails (P0571), the shift interlock solenoid never receives the 'brake pressed' signal, and the lever stays locked. Most vehicles have a manual override — a 'Shift Lock Release' button near the gear lever (sometimes hidden under a removable plastic cover). Press and hold this button while pressing the brake to release the lever in an emergency. This lets you move the vehicle to a repair location. Note: this is a workaround, NOT a fix — the brake switch must be repaired before the vehicle is safe to drive normally.
How much does it cost to fix P0571?
One of the cheaper OBD-II codes. Brake light switch (OEM): $10-$30. Stop lamp fuse: $1-$5. Connector cleanup: $5-$10. Wiring repair: $15-$60. Switch adjustment (if misaligned only): $0. DIY total: $15-$50 in 30-45 minutes. Shop labor: $80-$200 (most shops charge 1 hour minimum even though the job takes 15 minutes). PCM hardware failure (very rare): $800-$1,500. About 50-60% of P0571 cases resolve under $30 because the brake light switch itself failed. The biggest cost-saver: do the free brake light visual test (Step 2) BEFORE paying any shop diagnostic fee — many shops charge $120-$200 for diagnosis on a 30-second visual test you can do yourself.
Why does P0571 keep returning after replacement?
Four common reasons. (1) Misaligned new switch — most common reason. Switch must be installed at the right thread depth so plunger is slightly depressed at rest, fully extended when pedal is pressed. Wrong adjustment = code returns. Adjust 1/4 turn at a time. (2) Used aftermarket switch — generic replacements often have wrong plunger length or weak internal contacts. Use OEM only (Motorcraft, AC Delco, Mopar, etc.). (3) Wiring damage above the switch — even with new switch, damaged wire causes intermittent signal. Trace and repair wiring. (4) Cruise control system has TWO switches on some platforms — replacing only the 'A' switch when 'B' is failing causes recurrence. Service manual confirms 1-switch vs. 2-switch design. (5) Brake pedal arm bushing worn — common on older vehicles; pedal sits at wrong angle, no switch will work correctly. Replace bushing first.
What scanner do I need to fix P0571?
P0571 is simple enough that any OBD-II scanner can read the code, but having live data and ability to view brake switch input voltage in real time speeds diagnosis significantly. The iCarzone UR800 is a 5-inch LCD diagnostic scanner at $299.99 with full live data graphing including brake switch input voltage, freeze frame review, broad platform coverage (Ford, GM, VW/Audi, Toyota, Honda, BMW, Chrysler/Dodge/Jeep), and ability to clear codes after repair. The brake switch live data lets you verify the new switch is sending correct signals — voltage should change instantly between two states (typically 0V/5V or 5V/12V depending on platform) as you press and release the pedal. For most home DIYers, the UR800 is the right scanner choice — it has all the diagnostic capability needed for P0571 plus most other OBD-II codes you'll see over the years.
Can I just buy a generic brake light switch?
Not recommended — and this is one of the rare cases where the price difference is small enough that OEM is worth it. Generic brake light switches often have: wrong plunger length (won't trigger at correct pedal position); weaker internal contacts (fail again within months); slightly different connector polarity (causes false readings); plastic that doesn't match heat resistance specs (deforms in summer heat). The cost difference: generic switch $8-$15; OEM Motorcraft/AC Delco/Mopar $15-$30. The $7-$15 extra is the cheapest insurance available against repeat P0571 codes. Honda is particularly sensitive — Honda Genuine brake switch is recommended; aftermarket has documented failures on Civic and Accord. VW/Audi: original brake switch P/N 8E0 945 511 series is widely available; generic equivalents have higher failure rate.
Will P0571 cause my brake lights to stay on?
Yes — and this is one of the diagnostic tells. The brake light switch has two failure modes: stuck OPEN (brake lights never come on) or stuck CLOSED (brake lights always on). Both trigger P0571 but show different symptoms. Stuck OPEN: cruise control fails AND brake lights don't work AND shift lever may lock in Park (rear-end collision risk — immediate safety concern). Stuck CLOSED: brake lights always on (drains battery overnight + confuses other drivers + brake lights burn out faster). Either way, fix promptly. Modern vehicles also use the brake switch signal for other systems — stability control (ESC), anti-lock braking (ABS) calibration, hybrid regenerative braking — so failure can have wider effects than expected.
Which vehicles are most prone to P0571?
P0571 appears on any OBD-II vehicle (1996+ in USA) with electronic cruise control or shift interlock. High-volume platforms: VW Jetta/Golf/Passat/Tiguan (very common — P/N 8E0 945 511 series brake switch is documented failure point); Audi A3/A4/A6/Q5 (same VAG brake switch design); Ford F-150, Mustang, Escape (Motorcraft brake switch — typically lasts 80,000-150,000 miles); Toyota Camry/Tacoma/Corolla (Denso brake switch — generally reliable but can fail at high mileage); Honda Civic/Accord (Honda Genuine recommended; aftermarket has TSBs); Chevrolet Silverado/Tahoe/Suburban (AC Delco brake switch P/N 15109338 + retainer 10418918 — known service replacement); BMW 3/5 Series (also documented brake switch issues at 100,000+ miles); Mercedes-Benz (E-class, C-class — high mileage failures common). If you have one of these platforms, plan for the brake switch as the likely fix.
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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