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
P0500Vehicle Speed Sensor "A"Normal riskP0501Vehicle Speed Sensor "A" Range/PerformanceNormal riskP0502Vehicle Speed Sensor "A" Circuit Low InputNormal riskP0503Vehicle Speed Sensor "A" Intermittent/Erratic/HighNormal riskP0505Idle Control SystemNormal riskP0506Idle Air Control System RPM Lower Than ExpectedNormal riskP0507Idle Control System RPM Higher Than ExpectedNormal riskP0508Idle Air Control System Circuit LowNormal riskP0509Idle Air Control System Circuit HighNormal riskP0513Invalid Immobilizer KeyNormal riskP0520Engine Oil Pressure Sensor/Switch "A" CircuitHigh riskP0521Engine Oil Pressure Sensor/Switch "A" Range/PerformanceHigh riskP0522Engine Oil Pressure Sensor/Switch "A" Circuit LowHigh riskP0523Engine Oil Pressure Sensor/Switch "A" Circuit HighHigh riskP0524Engine Oil Pressure Too LowHigh riskP0560System VoltageHigh riskP0561System Voltage UnstableHigh riskP0562System Voltage LowHigh riskP0563System Voltage HighHigh risk