Check engine code library
The codes we see most on European cars — what they mean, the system affected, and whether it's safe to drive.
| # | Code | Brief description | Main system affected |
|---|---|---|---|
| 1 | P0300 – P0308 | Random/multiple or cylinder-specific misfire detected | Ignition, fuel delivery, or engine mechanical (coils, plugs, injectors, carbon buildup) |
| 2 | P0171 / P0174 | System too lean (Bank 1 / Bank 2) | Fuel/air metering & intake (vacuum/PCV leaks, boost leaks, MAF) |
| 3 | P0087 | Fuel rail/system pressure too low | High-pressure fuel system (HPFP, injectors, fuel delivery) |
| 4 | P0016 / P0017 | Crankshaft/camshaft position correlation fault (Bank 1 Sensor A/B) | Engine timing / variable valve timing (timing chain stretch, tensioner, VANOS/VVT) |
| 5 | P0128 | Coolant thermostat below regulating temperature | Cooling system (stuck-open thermostat) |
| 6 | P0299 | Turbocharger/supercharger underboost condition | Forced induction / turbo system (boost leaks, wastegate, charge pipes, actuators) |
| 7 | P0420 / P0430 | Catalyst system efficiency below threshold (Bank 1/2) | Emissions / exhaust (catalytic converter, O₂ sensors, upstream issues) |
| 8 | P0011 / P0012 / P0014 | Camshaft position timing over-advanced or over-retarded / system performance | Variable valve timing (VANOS/VVT solenoids, oil sludge, cam adjusters) |
| 9 | P2453 / P2463 / P2002 | DPF differential pressure sensor or restriction / efficiency below threshold | Diesel emissions (DPF clogging, sensors, regeneration — mainly diesel models) |
| 10 | P0730 / U-codes | Incorrect gear ratio, or lost communication with modules | Transmission (valve body/mechatronics) or network/CAN bus (battery/voltage, module faults) |
General information to help you understand your car. A code tells us which system reported a problem — not which part failed. Proper testing finds the cause.
Got a code? We'll find the cause.
Bring it in for a full diagnosis before you buy parts.