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The check engine light (MIL) illuminates without any noticeable driving symptoms. The car runs normally in all respects. This is commonly caused by EVAP system faults, minor sensor issues or a loose fuel cap.
Based on 0 driver confirmations
No commonly reported misdiagnoses for this fault yet. If you have replaced a part that did not fix this problem, submit a wrong diagnosis report — it helps other drivers avoid the same costly mistake.
Light came on with zero symptoms. Instead of going straight to a garage I bought a cheap OBD reader for £22. Pulled the code myself — P0420. Saved paying a diagnostic fee just to be told what the code was. Ended up being a lazy upstream O2 sensor, £55 to fix. Best £22 I ever spent.
Parts replaced: OBD reader, upstream O2 sensor
Had the light for months. Code was P0128 — engine never reaching proper temp. Thermostat was stuck open. Changed it myself, about 40 minutes work, £22 for the part. Heater works properly now for the first time in ages and fuel consumption improved noticeably.
Parts replaced: Thermostat and gasket
EML on, no symptoms at all. Read the code myself — P0457 fuel cap. Remembered I'd filled up the day before and probably hadn't clicked it properly. Tightened it. Drove for two days and the light cleared itself. Total cost: nothing. Try this first.
Parts replaced: Nothing
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