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
P2002Diesel Particulate Filter Efficiency Below Threshold (Bank 1)Normal riskP2003Diesel Particulate Filter Efficiency Below Threshold (Bank 2)Normal riskP207FReductant Quality PerformanceHigh riskP2096Post Catalyst Fuel Trim System Too Lean (Bank 1)Normal riskP2097Post Catalyst Fuel Trim System Too Rich (Bank 1)Normal riskP2098Post Catalyst Fuel Trim System Too Lean (Bank 2)Normal riskP2099Post Catalyst Fuel Trim System Too Rich (Bank 2)Normal riskP20B9Reductant Heater "A" Control Circuit/OpenNormal riskP20EESCR NOx Catalyst Efficiency Below Threshold (Bank 1)Normal riskP2100Throttle Actuator Control Motor Circuit/OpenHigh riskP2101Throttle Actuator Control Motor Circuit Range/PerformanceHigh riskP2119Throttle Actuator Control Throttle Body Range/PerformanceHigh riskP2122Throttle/Pedal Position Sensor/Switch "D" Circuit LowHigh riskP2123Throttle/Pedal Position Sensor/Switch "D" Circuit HighHigh riskP2127Throttle/Pedal Position Sensor/Switch "E" Circuit LowHigh riskP2128Throttle/Pedal Position Sensor/Switch "E" Circuit HighHigh riskP2135Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage CorrelationHigh riskP2138Throttle/Pedal Position Sensor/Switch "D"/"E" Voltage CorrelationHigh riskP2177System Too Lean Off Idle (Bank 1)Normal riskP2178System Too Rich Off Idle (Bank 1)Normal riskP2179System Too Lean Off Idle (Bank 2)Normal riskP2180System Too Rich Off Idle (Bank 2)Normal riskP2181Cooling System PerformanceNormal riskP2183Engine Coolant Temperature Sensor 2 Circuit Range/PerformanceNormal riskP2187System Too Lean At Idle (Bank 1)Normal riskP2188System Too Rich At Idle (Bank 1)Normal riskP2189System Too Lean At Idle (Bank 2)Normal riskP2190System Too Rich At Idle (Bank 2)Normal riskP2195O2 Sensor Signal Stuck Lean (Bank 1 Sensor 1)Normal riskP2196O2 Sensor Signal Stuck Rich (Bank 1 Sensor 1)Normal riskP2270O2 Sensor Signal Stuck Lean (Bank 1 Sensor 2)Normal riskP2271O2 Sensor Signal Stuck Rich (Bank 1 Sensor 2)Normal riskP2279Intake Air System LeakNormal riskP242FDiesel Particulate Filter Restriction – Ash AccumulationHigh riskP2452Diesel Particulate Filter "A" Pressure Sensor CircuitNormal riskP2453Diesel Particulate Filter "A" Pressure Sensor Circuit Range/PerformanceNormal riskP2454Diesel Particulate Filter "A" Pressure Sensor Circuit LowNormal riskP2455Diesel Particulate Filter "A" Pressure Sensor Circuit HighNormal riskP2458Diesel Particulate Filter Regeneration DurationHigh riskP2463Diesel Particulate Filter Restriction – Soot Accumulation (Bank 1)High riskP250FEngine Oil Level Too LowHigh risk