Will an Engine Management Light Fail My MOT?

If your engine management light (EML) has appeared on your dashboard, it should be cause for concern, both for the safety of your car and result of your MOT test.

The engine management light is your car’s way of telling you something isn’t quite right.

But does seeing it show up on your car’s dashboard mean your car will automatically fail its MOT test? Let’s break it down and answer that question.
 

What Does the Engine Management Light Mean?

The engine management light signals that there’s a potential issue with your car’s engine, emissions system, or exhaust.

Modern vehicles use a range of sensors that feed data to the engine control unit (ECU).

If the ECU detects a problem – whether it’s a faulty sensor, an engine misfire, or excessive emissions – it’ll turn on the EML to warn you.

However, the EML doesn’t specify exactly what’s wrong. It’s a general warning that something’s up and needs attention.

So even if it does just turn out to be a faulty sensor, you should get your car seen by a specialist at your local garage as soon as possible, particularly if your MOT is due soon.
 

Does Engine Management Light Appearing Mean MOT Failure?

Yes, your car will fail its MOT if your engine management light is showing.

If your EML is illuminated during an MOT test, it’s classed as a major fault – which means an automatic fail.
The reason? An active EML suggests your car may not be roadworthy or might be exceeding emissions limits, both of which are critical checks in the MOT.

However, there’s an exception for older vehicles. Petrol cars registered before 1st July 2003 and diesels registered before 1st July 2008 aren’t subject to the EML inspection during their MOT.

If you’re driving a historic car, you might be off the hook – but for most modern vehicles, a lit EML is a fail
 

Can I Drive with the EML On?

Technically, yes – but it’s not recommended. If the light is amber or orange, you might be able to drive to your destination or to a trusted garage.

However, continuing to drive without investigating the cause can worsen the problem and potentially damage your car.
If the EML is flashing, this indicates a more severe issue, such as an engine misfire that could damage your catalytic converter.

In this case, it’s best to pull over safely and seek professional help immediately.
 

Common Reasons for an EML to Appear

Here are some typical triggers for that dreaded dashboard warning:

• Faulty sensors – Such as the oxygen sensor or mass airflow sensor, which can disrupt emissions and engine performance.
• Catalytic converter problems – Often caused by carbon buildup or connection issues, reducing your car’s ability to control emissions.
• Ignition issues – Including failing spark plugs or coils, which can lead to poor combustion and misfires.
• Engine misfire – A sudden juddering or stuttering engine, often linked to ignition faults or head gasket leaks.
• Clutch or gearbox problems – Faulty sensors in the gear system can also trigger the EML.

Will the EML Go Away on Its Own?

Sometimes, yes – especially if the cause is something minor, like a loose fuel cap that’s been tightened.

However, if the light remains on, it’s best not to take chances. Your car’s ECU constantly monitors systems, and if it still detects a fault, the EML will stay lit.

In most cases, a professional diagnostic check is the quickest way to identify and resolve the issue.
 

Final Thoughts

The EML not only causes your car to fail its MOT, but it’s an indication that there’s an issue with your car which should be looked at immediately.

Ignoring the EML could result in worsening problems, potential safety hazards, and higher repair costs down the line, so it’s crucial to address it as soon as possible.

Taking swift action to resolve the EML issue can save you time, money, and stress in the long run.