Will My Car Pass Its MOT With an Engine Management Light On?
In short, no. If your engine management light is on and remains illuminated while the engine is running, your car will fail its MOT.
For most modern vehicles, an illuminated engine management light is classed as a major defect during the MOT test. If the warning light stays on, the vehicle cannot pass.
Even if the car appears to drive normally, the tester must record it as a failure if the light is illuminated.
Does the Engine Management Light Always Cause a Failure?
In most cases, yes.
During the MOT, the tester checks that dashboard warning lights operate correctly. If the engine malfunction indicator lamp remains on once the engine has started, it is recorded as a Major defect and results in a failure.
From an MOT perspective, the light must not be illuminated during the test.
Are There Any Age Based MOT Exemptions for Engine Management Light?
Yes. The inspection requirement for the engine management light only applies to certain vehicles based on their date of first registration.
Petrol vehicles first registered on or after 1 July 2003 are subject to this rule.
Diesel vehicles first registered on or after 1 July 2008 are also subject to this rule.
Vehicles registered before these dates may not automatically fail due to the engine management light alone. However, the vehicle must still meet all other MOT requirements.
Should You Investigate an Engine Management Light Before the MOT?
This can be a slightly more complicated situation.
If the engine management light (EML) is illuminated while the engine is running, the vehicle will fail its MOT. Because of this, many drivers want to have the fault diagnosed and repaired before the test takes place.
Having the warning light investigated beforehand is not necessarily a bad approach. However, it is important to remember that the vehicle could still fail its MOT on other unrelated items.
An engine management light can come on for hundreds of different reasons, ranging from minor faults to more complex repairs. The cost of resolving the issue can therefore vary significantly depending on the cause.
While the fault behind the warning light will ultimately need to be addressed for the vehicle to pass its MOT, there can be value in understanding the overall condition of the vehicle first. Carrying out the MOT provides a full picture of the vehicle’s roadworthiness and highlights any additional repairs that may be required.
This allows drivers to better understand the total scope of work and potential costs, rather than addressing one issue first and discovering further problems later.
Can I Just Clear the Fault Codes Before the MOT?
Clearing fault codes is never advised.
There is a possibility the warning light could reappear during the MOT test, which would result in a failure anyway. The vehicle has a fault that requires attention, and simply clearing codes does not resolve the issue.
Clearing codes can also make it more difficult when carrying out a proper diagnostic assessment. Stored fault information can be valuable in identifying the root cause of the problem. Removing that information may delay accurate diagnosis and repair.