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
P0400Exhaust Gas Recirculation "A" FlowNormal riskP0401Exhaust Gas Recirculation "A" Flow Insufficient DetectedNormal riskP0402Exhaust Gas Recirculation "A" Flow Excessive DetectedNormal riskP0403Exhaust Gas Recirculation "A" Control CircuitNormal riskP0404Exhaust Gas Recirculation "A" Control Circuit Range/PerformanceNormal riskP0405Exhaust Gas Recirculation Sensor "A" Circuit LowNormal riskP0406Exhaust Gas Recirculation Sensor "A" Circuit HighNormal riskP0407Exhaust Gas Recirculation Sensor "B" Circuit LowNormal riskP0408Exhaust Gas Recirculation Sensor "B" Circuit HighNormal riskP0409Exhaust Gas Recirculation Sensor "A" CircuitNormal riskP0420Catalyst System Efficiency Below Threshold (Bank 1)Normal riskP0421Warm Up Catalyst Efficiency Below Threshold (Bank 1)Normal riskP0422Main Catalyst Efficiency Below Threshold (Bank 1)Normal riskP0430Catalyst System Efficiency Below Threshold (Bank 2)Normal riskP0431Warm Up Catalyst Efficiency Below Threshold (Bank 2)Normal riskP0432Main Catalyst Efficiency Below Threshold (Bank 2)Normal riskP0440Evaporative Emission SystemNormal riskP0441Evaporative Emission System Incorrect Purge FlowNormal riskP0442Evaporative Emission System Leak Detected (Small Leak)Normal riskP0443Evaporative Emission System Purge Control Valve "A" CircuitNormal riskP0444Evaporative Emission System Purge Control Valve Circuit OpenNormal riskP0445Evaporative Emission System Purge Control Valve Circuit ShortedNormal riskP0446Evaporative Emission System Vent Control CircuitNormal riskP0447Evaporative Emission System Vent Control Circuit OpenNormal riskP0448Evaporative Emission System Vent Control Circuit ShortedNormal riskP0449Evaporative Emission System Vent Valve/Solenoid CircuitNormal riskP0450Evaporative Emission System Pressure Sensor/Switch "A" CircuitNormal riskP0451Evaporative Emission System Pressure Sensor/Switch "A" Circuit Range/PerformanceNormal riskP0452Evaporative Emission System Pressure Sensor/Switch "A" Circuit LowNormal riskP0453Evaporative Emission System Pressure Sensor/Switch "A" Circuit HighNormal riskP0454Evaporative Emission System Pressure Sensor/Switch "A" Circuit IntermittentNormal riskP0455Evaporative Emission System Leak Detected (Large Leak)Normal riskP0456Evaporative Emission System Leak Detected (Very Small Leak)Normal riskP0457Evaporative Emission System Leak Detected (Fuel Cap Loose/Off)Normal riskP0458Evaporative Emission System Purge Control Valve Circuit LowNormal riskP0459Evaporative Emission System Purge Control Valve Circuit HighNormal riskP0460Fuel Level Sensor "A" CircuitNormal riskP0461Fuel Level Sensor "A" Circuit Range/PerformanceNormal riskP0462Fuel Level Sensor "A" Circuit LowNormal riskP0463Fuel Level Sensor "A" Circuit HighNormal riskP0464Fuel Level Sensor "A" Circuit IntermittentNormal riskP0496Evaporative Emission System High Purge FlowNormal riskP0497Evaporative Emission System Low Purge FlowNormal riskP0498Evaporative Emission System Vent Valve Control Circuit LowNormal riskP0499Evaporative Emission System Vent Valve Control Circuit HighNormal risk