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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P050B Code Cold Start Ignition Timing Performance P0880 Code TCM Power Input Signal Diagnosis and Fix P0266 Code Diagnose Cylinder 2 Contribution/Balance P0691 Code Fan 1 Control Circuit Low Diagnosis P2535 Code Ignition Switch Run/Start Position Circuit High P2684 Code Actuator Supply Voltage C Circuit/Open P054C Code Cold Start B Cam Timing Over-Advanced Bank 2 P2704 Code Friction Element E Apply Time Range/Performance P3449 Code Cylinder 7 Intake Valve Control Circuit/Open P2761 Code TCC Pressure Control Solenoid Circuit/Open P2BAA Code NOx Exceedance - Low Reductant Consumption P0193 Code Fuel Rail Pressure Sensor Circuit High Input P06C9 Code Cylinder 5 Glow Plug Incorrect—Diagnose FirstDiesel Diagnostics P0466 Code EVAP Purge Flow Sensor Range/Performance P2716 Code Pressure Control Solenoid D Electrical Guide P0208 Code Injector Circuit/Open – Cylinder 8 P050E Code Cold Start Engine Exhaust Temperature Too Low P0843 Code Transmission Fluid Pressure Sensor A Circuit High P2784 Code Input/Turbine Speed Sensor A/B Correlation P0532 Code A/C Pressure Sensor Circuit Low—What to Test P0630 Code VIN Not Programmed or Incompatible—ECM/PCM P0263 Code Cylinder 1 Contribution/Balance P2703 Code Friction Element D Apply Time Range/Performance P0139 Code O2 Sensor Circuit Slow Response (Bank 1, Sensor 2) P2418 Code EVAP System Switching Valve Control Circuit/Open P0676 Code Cylinder 6 Glow Plug Circuit/Open P2510 Code ECM/PCM Power Relay Sense Circuit Range/Performance P208A Code Reductant Pump A Control Circuit/Open P07A3 Code Transmission Friction Element A Stuck On P2073 Code Diagnose MAP/MAF-Throttle Correlation at Idle P3401 Code Diagnose a Cylinder 1 Deactivation Circuit Open P018D Code Fuel Pressure Sensor B Circuit High P2813 Code Pressure Control Solenoid G Range/Performance P2626 Code O2 Sensor Pumping Current Trim Circuit/Open P043F Code EVAP Reference Orifice High Flow — Diagnosis and Fix Guide P083B Code Transmission Fluid Pressure Sensor/Switch G Performance P0003 Code Fuel Volume Regulator Control Circuit Low P0272 Code Cylinder 4 Contribution/Balance Causes and Fixes P2638 Code Torque Management Feedback Signal A Range/Performance P0933 Code Hydraulic Pressure Sensor Range/Performance P0560 Code System Voltage Malfunction Diagnosis and Fix P054A: Cold Start B Camshaft Position Timing Over-Advanced (Bank 1) P061C Code Internal Control Module Engine RPM Performance P062C Code Internal Control Module Vehicle Speed Guide P2432 Code AIR Pressure Sensor Circuit Low Bank 1 P2681 Code Coolant Bypass Valve Circuit Open Fix Guide P2302 Code Ignition Coil A Secondary Circuit Fix Guide P06A7 Code Sensor Reference Voltage B Range/Performance P3000 Code Toyota Battery Control System Diagnosis Guide P2419 Code EVAP Switching Valve Circuit Low
655 codes · page 2 of 14
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 →