What’s wrong with your car?

Look up a fault code or pick your vehicle — get an instant, mechanic-grade answer.

✔ Official NHTSA recall data ✔ Mechanic-reviewed guidance ✔ Always free

🔧 Fault codesOBD-II P, B, C & U codes explained. 🩺 SymptomsWon't start, rough idle, overheating… 💡 Warning lightsWhat each dashboard light means. 🚗 By vehicleCommon problems by make & model. ⚙️ Car partsSymptoms, codes & cost per part. 🛟 Car recallsMost-recalled models & recalls by brand (NHTSA). 🧰 Free toolsScanner, VIN, recalls & more.

Most-searched fault codes

P0420 — Catalyst System Efficiency Below Threshold (Bank 1)P0171 — System Too Lean (Bank 1)P0300 — Random/Multiple Cylinder Misfire DetectedP0301 — Cylinder 1 Misfire DetectedP0174 — System Too Lean (Bank 2)P0455 — EVAP System Leak Detected (Large Leak)P0442 — EVAP System Leak Detected (Small Leak)P0401 — EGR Insufficient Flow DetectedP0128 — Coolant Thermostat (Below Regulating Temperature)P0101 — Mass Air Flow Sensor Range/PerformanceP0430 — Catalyst System Efficiency Below Threshold (Bank 2)P0440 — EVAP System Malfunction (General)P0135 — O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)P0141 — O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)P0402 — EGR Excessive Flow DetectedP0700 — Transmission Control System MalfunctionP0340 — Camshaft Position Sensor Circuit MalfunctionP0335 — Crankshaft Position Sensor Circuit MalfunctionP0130 — O2 Sensor Circuit Malfunction (Bank 1, Sensor 1)P2195 — O2 Sensor Signal Stuck Lean (Bank 1, Sensor 1)P0011 — "A" Camshaft Position — Timing Over-Advanced (Bank 1)P0014 — "B" Camshaft Position — Timing Over-Advanced (Bank 1)P0325 — Knock Sensor Circuit Malfunction (Bank 1)P0118 — Engine Coolant Temperature Sensor Circuit HighP2187 — System Too Lean at Idle (Bank 1)P0500 — Vehicle Speed Sensor (VSS) MalfunctionP0131 — O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)P0137 — O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)P0133 — O2 Sensor Slow Response (Bank 1, Sensor 1)P0021 — "A" Camshaft Position — Timing Over-Advanced (Bank 2)P0117 — Engine Coolant Temperature Sensor Circuit LowP2189 — System Too Lean at Idle (Bank 2)P2293 — Fuel Pressure Regulator 2 PerformanceU0100 — Lost Communication With ECM/PCM "A"P0012 — "A" Camshaft Position — Timing Over-Retarded (Bank 1)P0341 — Camshaft Position Sensor "A" Circuit Range/Performance (Bank 1)P0113 — Intake Air Temperature Sensor 1 Circuit High (Bank 1)P0506 — Idle Air Control System RPM Lower Than ExpectedP0507 — Idle Air Control System RPM Higher Than ExpectedP0456 — EVAP System Leak Detected (Very Small Leak)P0302 — Cylinder 2 Misfire DetectedP0303 — Cylinder 3 Misfire DetectedP0304 — Cylinder 4 Misfire DetectedP0172 — System Too Rich (Bank 1)P0102 — Mass Air Flow (MAF) Circuit Low InputP0299 — Turbocharger / Supercharger "A" UnderboostP0087 — Fuel Rail / System Pressure Too LowP0520 — Engine Oil Pressure Sensor / Switch CircuitP0103 — Mass Air Flow (MAF) Circuit High InputP0112 — Intake Air Temperature Sensor 1 Circuit Low (Bank 1)P0116 — Engine Coolant Temperature Sensor Circuit Range/PerformanceP0125 — Insufficient Coolant Temperature for Closed-Loop Fuel ControlP0016 — Crankshaft / Camshaft Position Correlation (Bank 1, Sensor A)P0446 — EVAP System Vent Control Circuit MalfunctionP0449 — EVAP System Vent Valve / Solenoid Circuit MalfunctionP0741 — Torque Converter Clutch Circuit Performance / Stuck OffP0562 — System Voltage LowP0563 — System Voltage HighP0234 — Turbocharger / Supercharger "A" Overboost ConditionP0327 — Knock Sensor 1 Circuit Low (Bank 1)P0106 — MAP / Barometric Pressure Circuit Range/PerformanceP0107 — MAP / Barometric Pressure Circuit Low InputP0108 — MAP / Barometric Pressure Circuit High InputP0121 — Throttle / Pedal Position Sensor "A" Circuit Range/PerformanceP0122 — Throttle / Pedal Position Sensor "A" Circuit Low InputP0123 — Throttle / Pedal Position Sensor "A" Circuit High InputP0443 — EVAP Purge Control Valve Circuit MalfunctionP0444 — EVAP Purge Control Valve Circuit OpenP0155 — O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)P0160 — O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 2)P0606 — ECM/PCM Processor FaultP0496 — EVAP System High Purge FlowP0175 — System Too Rich (Bank 2)P0336 — Crankshaft Position Sensor "A" Circuit Range/Performance

More flagship codes (P0174, P0455, P0442, P0401, P0128, P0101…) are being published — prioritized by real-world fault frequency.

Browse by symptom

Engine MisfireRough IdleCheck Engine Light FlashingLoss of PowerPoor Fuel EconomyEngine StallingHard StartingEngine OverheatingCar Won’t Start (Battery OK)Engine KnockingWhite Smoke From ExhaustBlack Smoke From ExhaustTransmission SlippingCar Shaking at IdleHigh Idle RPMJerking During AccelerationFuel Smell in the CarCold-Start StallingSlow Acceleration / Lack of PowerVibration While Driving

Dashboard warning lights

Check Engine LightABS Warning LightAirbag (SRS) Warning LightBattery / Charging Warning LightOil Pressure Warning LightEngine Temperature Warning LightTraction Control LightDPF (Diesel Particulate Filter) Warning LightAdBlue (DEF) Warning LightEPC (Electronic Power Control) Light

Common problems by model

Fiat StradaVolkswagen PoloChevrolet OnixHyundai HB20Fiat ArgoNissan VersaChevrolet AveoHyundai CretaNissan KicksFord F-150Chevrolet SilveradoToyota RAV4Honda CR-VRam 1500Toyota CamryHonda CivicToyota Corolla

Browse all makes & models →

Safety recalls by brand

Official NHTSA safety-recall records for 23 brands, 135 models and every year — the defect, the risk, and the free fix.

Ford recalls Chevrolet recalls Toyota recalls Honda recalls Jeep recalls Ram recalls Nissan recalls Hyundai recalls GMC recalls Volkswagen recalls BMW recalls Tesla recalls

Most-recalled cars & full recall statistics →

Car parts: symptoms, codes & cost

Oxygen (O2) SensorCatalytic ConverterMass Air Flow (MAF) SensorManifold Absolute Pressure (MAP) SensorSpark PlugsIgnition CoilEGR ValveEVAP Purge ValveEngine ThermostatCoolant Temperature SensorCamshaft Position SensorCrankshaft Position SensorThrottle Position (TPS) SensorKnock SensorIntake Air Temperature (IAT) SensorVVT Solenoid (Oil Control Valve)Idle Air Control (IAC) ValveFuel PumpFuel InjectorOil Pressure SensorPCV ValveCar BatteryAlternatorVehicle Speed Sensor (VSS)ABS Wheel Speed SensorBrake PadsBrake Rotors (Discs)Wheel BearingStarter MotorSerpentine BeltWater PumpRadiatorCabin Air FilterEngine Air FilterTurbochargerTorque ConverterTransmission Shift SolenoidFuel Pressure RegulatorFuel FilterTiming BeltA/C CompressorClutchControl ArmTie Rod EndShock Absorber / Strut

Each part guide links straight to the fault codes it triggers and where to buy it.

Free car tools

🔌 OBD-II ScannersRead the exact code behind your check engine light. 🛟 Recall CheckSee if your car has an open safety recall (official NHTSA data). 🔎 VIN DecoderDecode your VIN: country, maker, model year and plant. 🛠️ Maintenance ScheduleSee what service is due at your mileage. 🛞 Tire Size DecoderDecode a tire size and compare dimensions. ⛽ Fuel CalculatorConvert MPG ↔ L/100km ↔ km/L and trip cost.

Start with what you’re seeing

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