HELP/02 — TROUBLE CODES
What does your check-engine code mean?
Scanned a P-code with an OBD-II reader? Look it up below. Every guide explains what the code means, how urgent it is, what usually triggers it — and, crucially, how it reads differently on European makes like BMW, Mercedes, Audi and VW.
The engine isn't reaching its normal operating temperature in the time the ECU expects — usually because the thermostat is stuck open and over-cooling the engine.
CoolingThe engine is getting too much air for the fuel it's burning. The ECU added fuel to compensate and ran out of room — so it set a lean code.
Fuel / Air intakeThe engine control unit detected misfires it couldn't pin to a single cylinder — combustion is failing in more than one place.
Ignition / Fuel / EngineThe engine is misfiring in one specific place: cylinder 1. Combustion there is failing often enough for the ECU to flag it.
Ignition / Fuel / EngineBased on the oxygen sensor after the catalytic converter, the ECU thinks the cat isn't cleaning the exhaust as well as it should.
Emissions / Catalytic converterThe evaporative emission control (EVAP) system failed its pressure test — fuel vapor is escaping through what the ECU calls a large leak (a 'gross leak,' in older terms).
Emissions / EVAPMore codes are added regularly. Don't see yours? Book a diagnostic — we read the live data and tell you exactly what it means on your car.
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