Support · Fault Code Lookup

OBD-II Fault Code Guides

Mechanic-written repair guides for every trouble code — what it really means, what actually causes it, and how to fix it before you replace expensive parts.

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P0483 Code Cooling Fan System Performance P2A03 Code O2 Sensor Performance Bank 2 Sensor 1 P013C Code O2 Slow Response Rich to Lean B2S2 P285A Code Clutch B Pressure Disengagement Fault P0965 Code Pressure Solenoid B Range/Performance P0752 Code Shift Solenoid A Stuck On P2090 Code B Cam Actuator Circuit Low Bank 1 P0357 Code Ignition Coil G Primary Circuit Open P0677 Code Cylinder 7 Glow Plug Circuit Fault P2189 Code System Too Lean at Idle Bank 2 P0757 Code Shift Solenoid B Stuck On P0219 Code Fix Engine Overspeed ConditionEngine Overspeed P242F Code Fix DPF Restriction from Ash AccumulationDiesel Particulate Filter P0661 Code Fix Intake Manifold Tuning Valve Circuit LowDiagnostic Guide P02E9 Code Fix Diesel Intake Air Position Sensor Circuit HighDiagnostic Guide P2A01 Code Fix O2 Sensor Range/Performance (Bank 1 Sensor 2)Diagnostic Guide P2308 Code Fix Ignition Coil C Secondary CircuitDiagnostic Guide P0551 Code Fix Power Steering Pressure Sensor PerformanceOBD-II Code P068A Code Fix ECM/PCM Power Relay Shuts Off Too EarlyECM Power Relay P013A Code O2 Sensor Slow Response Rich to Lean (Bank 1 Sensor 2) P00BD Code Exhaust Gas Temperature Sensor Range/Performance P0305 Code Swap the Coil Before You Spend a DollarCylinder 5 Misfire P0713 Code Fix Trans Fluid Temp Sensor High (Test First)iCarzone UR1000 P0245 Code Fix Boost Control Solenoid A Circuit Low (Wiring First)boost control solenoid P018C Code Mercedes C300 L (2022-2024) Fix Fuel Temp Sensor with ICARZONE UR800 P2649 Code VTEC Solenoid High Voltage — DIY Fix Guide P2647 Code 'A' Rocker Arm Actuator System Stuck On (Bank 1) — Don't Replace Your VTEC Solenoid Yet P2001 Code Fix NOx Adsorber Efficiency Below Threshold Bank 2 P0276 Code Fix Cylinder 6 Injector Circuit Low (Wiring First)Cylinder 6 P2111 Code Fix Throttle Actuator Control Stuck Open (Clean First)drive-by-wire P0524 Code Fix Engine Oil Pressure Too Low (Stop and Check Oil)engine oil pressure too low P0246 Code Fix Wastegate Boost Solenoid A High (Wiring First) P2178 Code Fix System Too Rich Off Idle Bank 1 (Test First)Fuel System Rich P00FF Code BCM Asked for CEL — Scan ALL Modules to Find Why P2404 Code EVAP Leak Detection Pump Sense Circuit Range/Performance P0410 Code The Cold-Start Air Pump Isn't Doing Its Job P0232 Code Check the Fuel Pump Relay Before the Pump Itself P3497 Code Check Your Oil Dipstick Before Anything Else P0315 Code Run the Relearn Before Buying Any Crank Sensor P1299 Code Engine in Limp Mode? Suspect the CHT Sensor First P0523 Code Sensor Says High Oil Pressure — Use a Gauge to Verify U0401 Code Invalid Data on the CAN Bus, Not a Failed PCM P0607 Code Before You Replace the PCM, Test These 4 Things P0138 Code Downstream O2 Stuck High — A Catalyst Warning Sign P1705 Code That Flashing 'D' Light Means Range Sensor Trouble P0132 Code Upstream O2 Says Rich — Is the Sensor Lying? P2402 Code That Cold-Start Rattle Is the EVAP Pump, Not a Leak P0236 Code Lost Boost on Your EcoBoost? Check Vacuum First P0351 Code Cylinder 1 Won't Spark — Here's the 5-Minute Test P2099 Code Sensor Reads Rich, But the Trim Is the Real Story
553 codes · page 1 of 12
01 Read your code

Every code is four signals in five characters.

P
System
P = Powertrain (engine & transmission)
0
Type
0 = generic SAE standard · 1 = make-specific
4
Subsystem
The subsystem the code points to
2
Fault
The specific fault
0
Index
Index within that subsystem
P
Powertrain

Engine, fuel, ignition, emissions and transmission. By far the most common — most check-engine lights start with P.

B
Body

Interior comfort and safety: airbags, lighting, power windows, seats, climate control.

C
Chassis

Mechanical systems outside the body: ABS, traction control, steering, suspension, wheel-speed sensors.

U
Network

Communication between control modules over the car's data bus (CAN). Often points to wiring or a module that has gone quiet.

Generic vs manufacturer-specific: a 0 in the second position means the code follows the SAE standard and means the same on every car — those are the ones in this library. A 1 (and sometimes 3) means the carmaker defined it themselves, so the same code can mean different things on a BMW and a Toyota. For those, read the exact definition on your scan tool.

02 When the light comes on

Four moves, in order.

  1. Is it flashing?

    A flashing check-engine light usually means an active misfire that can damage the catalytic converter — ease off the throttle and get it looked at promptly. A steady light is rarely an emergency; investigate soon.

  2. Scan for the codes

    Plug in a scan tool and read the stored codes. Note every code and its freeze-frame data — the first one set is often the root cause of the rest.

  3. Look it up

    Search the code here to understand what system it points to, how serious it is, and the parts most often behind it — before you spend a cent on parts.

  4. Fix, clear, confirm

    Repair the root cause, clear the code, then drive and re-scan. If it comes straight back, the underlying fault is still there — keep diagnosing, don't just keep clearing.

From code to cause

A code tells you the system. A scanner tells you the part.

Reading the code is step one. ICARZONE tools go further — live data, bidirectional actuator tests and OE-level access pinpoint the actual faulty component, then clear the code once it's fixed.

Explore the toolsCompare models

Can't find your code, or got a P1/B1/C1/U1 code? Those are manufacturer-specific. Tell our team the code and your vehicle (make, model, year) and we'll help you read it — or grab the exact OE definition with an ICARZONE tool. Contact support →