OBD-II Fault Codes
Look up a code from your scanner. Every code page shows the risk first, then what it means, possible causes and how it is diagnosed.
Codes and titles follow SAE J2012 · Maker notes verified per make and engine · How we verify
Browse by system
Powertrain codes by subsystem
P00xxFuel, air metering and auxiliary emission controlsP01xxFuel and air meteringP02xxFuel and air metering (injector circuit)P03xxIgnition system and misfireP04xxAuxiliary emission controlsP05xxVehicle speed, idle control and auxiliary inputsP06xxComputer and auxiliary outputsP07xxTransmissionP2xxxAdditional generic codes (fuel, air, emissions)
Most searched codes
P0420Catalyst System Efficiency Below Threshold (Bank 1)Normal riskP0300Random/Multiple Cylinder Misfire DetectedHigh riskP0171System Too Lean (Bank 1)Normal riskP0128Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)Normal riskP0455Evaporative Emission System Leak Detected (Large Leak)Normal riskP0401Exhaust Gas Recirculation "A" Flow Insufficient DetectedNormal riskP0442Evaporative Emission System Leak Detected (Small Leak)Normal riskP0700Transmission Control System (MIL Request)Normal riskP0299Turbocharger/Supercharger "A" Underboost ConditionNormal riskP0172System Too Rich (Bank 1)Normal riskP0135O2 Sensor Heater Circuit (Bank 1 Sensor 1)Normal riskP0113Intake Air Temperature Sensor 1 Circuit HighNormal risk
How to read a fault code
The letter is the system, the first digit says generic or maker-specific, the next digit the subsystem and the last two the exact fault. Fault Code Lookup →All fault codes
C0020ABS Pump Motor ControlHigh riskC0021Brake Booster PerformanceHigh riskC0031Left Front Wheel Speed SensorHigh riskC0034Right Front Wheel Speed SensorHigh riskC0035Left Front Wheel Speed Sensor Circuit (GM)High riskC0037Left Rear Wheel Speed SensorHigh riskC003ARight Rear Wheel Speed SensorHigh riskC0040Right Front Wheel Speed Sensor Circuit (GM)High riskC0042Brake Pedal Position Sensor Circuit "A"High riskC0044Brake Pressure Sensor "A"High riskC0045Left Rear Wheel Speed Sensor Circuit (GM)High riskC0049Brake Fluid LevelHigh riskC004ABrake Lining Wear SensorHigh riskC0050Right Rear Wheel Speed Sensor Circuit (GM)High riskC0051Steering Wheel Position SensorHigh riskC0061Lateral Acceleration SensorHigh riskC0062Longitudinal Acceleration SensorHigh riskC0063Yaw Rate SensorHigh riskC0072Brake Temperature Too HighHigh riskC0077Low Tire PressureNormal riskC0110Pump Motor Circuit (GM)High riskC0121Valve Relay Circuit (GM)High riskC0500Left Front Wheel Speed Sensor "A" Circuit/OpenHigh riskC0506Right Front Wheel Speed Sensor "A" Circuit/OpenHigh riskC050CLeft Rear Wheel Speed Sensor "A" Circuit/OpenHigh riskC0512Right Rear Wheel Speed Sensor "A" Circuit/OpenHigh riskC0526Steering Angle Sensor ModuleHigh risk