Will a warning light fail your MOT?
Some will. On most petrol cars first used from July 2003 and diesels from July 2008, an engine management light that stays on is a major defect and fails the test. So is a warning light showing a fault with the ABS, airbags, stability control, power steering, electronic parking brake or tyre pressure system.
Updated 31 October 2026 · By Odomint
How the tester checks a warning light
The tester switches on the ignition, and on some cars starts the engine, and watches each warning light. A light that stays on to show a fault is what fails. For the engine light, the DVSA’s MOT inspection manual’s wording is "engine MIL inoperative or indicating a malfunction".
For the engine light and the ABS light, a light that does not work at all fails too. So on those two, a bulb that has been removed to hide a fault fails as surely as a light that is showing one.
The lights that fail, and the cars they apply to
Engine management light: a major defect on petrol cars, including hybrids, first used on or after 1 July 2003, on gas and bi-fuel cars first used on or after 1 July 2008, and on diesel cars, including hybrids, first used on or after 1 July 2008. Kit cars, amateur-built cars and American pickups are not required to have one.
ABS: a warning light that does not work, or shows a fault, is a major defect.
Electronic parking brake: a major defect if its warning light shows a malfunction.
Electronic stability control: a major defect if its warning light shows a fault. The manual tells testers to fail it only when they are sure the light means an ESC fault.
Airbags and seatbelt pre-tensioners: a major defect if the airbag system’s warning light shows a malfunction.
Electric power steering: a major defect if its warning light shows a fault.
Tyre pressure monitoring system: a major defect if the system is faulty or plainly not working, on cars first used on or after 1 January 2012.
Brake fluid: a warning light that is on, or does not work properly, is a minor defect. It is recorded on the certificate but does not fail the test.
The lights that do not fail on their own
A brake pad wear light is not grounds for failure by itself. What fails is pads that have worn down to the indicator, which the tester checks directly.
A tyre pressure light that is on because a tyre is low is not the same as a faulty system. When it is not clear which it is, the tester can add an advisory instead.
A passenger airbag light showing the airbag is switched off is not a defect, and a dashboard message is not a defect in itself, although it can help the tester confirm a fault.
Before the test
If a light is on, have the fault read and fixed before the test rather than after it. Most garages can read the stored fault code in a few minutes. Clearing the code without fixing the cause can turn the light off for a while, but the fault is still there and the light can come back.
Majors fail the test. If your current certificate is still valid and nothing was marked dangerous, you can still drive the car away to get it fixed, as long as it is roadworthy. The full rules are in the related guide below on driving a car that failed its MOT.
Odomint shows every defect and advisory recorded at your car’s past MOTs, free from the DVSA’s records, so you can see what testers have noted before.
Common questions
Will my car fail its MOT with the engine light on?
On most cars, yes. It is a major defect on petrol cars first used from 1 July 2003 and diesel cars first used from 1 July 2008, including hybrids.
Does the tyre pressure warning light fail an MOT?
Only if the system is faulty or not working, and only on cars first used from 1 January 2012. A light that is on because a tyre is low is not a fault in the system.
Does the ABS light fail an MOT?
Yes. An ABS warning light that shows a fault, or does not work, is a major defect.
Does the airbag light fail an MOT?
Yes, if it shows a fault with the airbag system. A passenger airbag light showing the airbag is switched off is not a defect.
Does the brake pad warning light fail an MOT?
Not on its own. The tester checks the pads, and pads worn down to the wear indicator are a major defect.
Your MOT and tax dates, with a reminder before each
Add your number plate and Odomint reads your MOT and tax dates from the DVSA and DVLA, shows every past MOT result and advisory, and reminds you before each one is due. Free for one car.
Sources
Every figure on this page was checked against these on 31 October 2026.
- DVSA MOT inspection manual: 1. Brakes
- DVSA MOT inspection manual: 2. Steering
- DVSA MOT inspection manual: 5. Axles, wheels, tyres and suspension
- DVSA MOT inspection manual: 7. Other equipment
- DVSA MOT inspection manual: 8. Nuisance (emissions)