Engine warning light (MIL) on
How it can appear on an MOT certificate
- “Engine MIL inoperative or indicating a malfunction”
- “Malfunction indicator lamp indicates a malfunction”
What it is
The engine management or malfunction indicator lamp (MIL), often an amber engine symbol, lights when the engine's computer detects a fault, usually emissions-related.
Why it matters
A lit engine warning light is an MOT fail. The fault behind it can be minor, such as a sensor, or more significant.
What to check when viewing a car
The light should come on briefly with the ignition and then go out. If it stays on, a garage can read the fault code before you buy.
Has the car you're looking at had this before?
Free: every MOT, every defect explained in plain English, mileage, tax and ULEZ.
What the MOT categories mean
- Dangerous
- A direct and immediate risk to road safety, or a serious impact on the environment. The car fails and shouldn't be driven until it's repaired.
- Major
- It may affect the car's safety, put other road users at risk or harm the environment. The car fails and should be repaired straight away.
- Minor
- No significant effect on safety or the environment. The car passes, but it should be repaired as soon as possible.
- Advisory
- Something to keep an eye on that could need repairing in future. The car passes.
Related: exhaust and emissions
- Exhaust leak
- Exhaust insecure or mountings damaged
- Emissions over the limit
- Diesel smoke over the limit
- Catalytic converter missing or not working
Buying a used car?
General information about this type of MOT defect, not advice about a particular car. How serious it is depends on the car; have any car you're buying inspected by a qualified mechanic.