Will My Car Fail Its MOT Due to an Engine Warning Light?

The engine warning light (sometimes called the check engine light) can be alarming when it suddenly appears on your dashboard. Whether it will cause an MOT failure depends on the issue behind the warning and how it affects safety or emissions.

What the MOT Test Checks: the MOT focuses on safety, roadworthiness, and emissions rather than the light itself. However, many of the faults that trigger the engine warning light are examined closely by the tester.

If the warning light is on because of a malfunctioning exhaust system, emissions issue, or another problem that affects legal limits, your car will almost certainly fail. Minor sensor issues that do not affect performance may pass, but they can still be recorded as advisories.

Can an Engine Warning Light Cause an MOT Failure? Yes, if it indicates a defect in components such as the engine, emissions system, or exhaust. A faulty catalytic converter or fuel system issue can be discovered during the emissions test even if the light itself is ignored.

If you are concerned, run a diagnostic scan or take the car to a qualified mechanic before the MOT. Tools such as our Car BHP Check can help you assess engine performance and uncover hidden issues.

You should also review the vehicle's existing MOT history and any previous advisories via our MOT Check page so you know what to expect before arriving at the test centre.

Conclusion

An engine warning light can lead to an MOT failure if it points to a defect that compromises safety, roadworthiness, or emissions. Diagnose and repair any issues before the test to avoid an unexpected fail, and keep track of previous results using the MOT Check tool.