Why did my car fail its MOT?
The most common MOT failures are faulty lights and signalling, worn or damaged tyres, brake problems, suspension issues, and poor driver visibility such as worn wipers or a chipped windscreen. Many of these are cheap or free to check and fix before your test.
Most cars that fail their MOT do so for everyday reasons, not major mechanical faults. Knowing the usual culprits means you can check the simple things yourself, fix them cheaply, and avoid an avoidable fail and a wasted trip.
The most common MOT failure reasons
Year after year, DVSA figures show the same familiar group at the top. In rough order of how often they occur, the biggest areas are:
| Failure area | Typical examples | Fix it yourself? |
|---|---|---|
| Lighting and signalling | Blown bulbs, misaligned headlights, faulty indicators | Often yes |
| Suspension | Worn bushes, springs, shock absorbers | No, use a garage |
| Brakes | Worn pads, imbalance, a warning light | No, use a garage |
| Tyres | Below 1.6mm tread, damage, wrong pressure | No, use a garage |
| Driver visibility | Worn wipers, chipped windscreen, low screen wash | Often yes |
Lighting and signalling: the number one fail
A single blown bulb is enough to fail an MOT, and it is the most common reason of all. Before your test, switch on every light in turn, including headlights, brake lights, indicators, fog lights and number plate lights. Ask someone to stand behind and in front of the car while you check, or use a reflection. Bulbs are inexpensive and quick to replace.
Tyres and brakes
The legal minimum tyre tread depth is 1.6mm across the central three quarters of the tyre. Check for uneven wear, cracks and bulges too. Brakes are harder to self-assess, but if you hear grinding or squealing, or the car pulls to one side when braking, get them checked before the test rather than after a fail.
Simple checks to do before your MOT
- Check every light works, including brake lights and indicators.
- Top up the screen wash and make sure the wipers do not smear.
- Check tyre tread and pressures, and look for damage.
- Make sure the windscreen has no large chips in the driver’s line of sight.
- Clear any dashboard warning lights that stay on, and clean the number plates and mirrors.
If a warning light is showing and you are not sure what it means, our guide to dashboard warning lights explains the colours and what to do.
What happens after a fail?
A failed item must be repaired before your car is back to a legal standard. If you leave it at the same garage, a retest within 10 working days is often free or reduced. For what you can expect to pay for the test itself, see how much an MOT should cost. When you need the work done, you can compare trusted local garages in minutes.
Key takeaways
- Lighting and signalling faults are the single most common MOT failure.
- Tyres, brakes and suspension account for a large share of the rest.
- Worn wiper blades, low screen wash and a chipped windscreen can all fail a test.
- A quick pre-test check at home prevents many avoidable failures.
- A failed item must be repaired before the car is legal to drive again.
Frequently asked questions
What are the most common MOT failures?
Lighting and signalling faults are the most common, followed by suspension, brakes, tyres and driver visibility (such as wipers and the windscreen). Together these account for the large majority of failures, and several are simple to check yourself before the test.
Can I fix MOT failures myself?
Some, yes. Replacing a blown bulb, topping up screen wash or fitting new wiper blades are simple, cheap jobs most drivers can do at home. Brakes, suspension and tyres should be left to a qualified garage, as they directly affect safety.
Can I drive my car if it fails the MOT?
Only in limited cases, such as driving to a pre-booked repair or retest, and only if the car is roadworthy and the previous certificate has not expired. If the tester lists a dangerous fault, you must not drive it at all until it is fixed.
How long do I have to fix an MOT failure?
There is no set repair deadline, but you cannot legally drive on a failed MOT once the old certificate expires, except to a booked test or repair. A retest within 10 working days at the same garage is often free or reduced, so it pays to act quickly.
Does a warning light cause an MOT failure?
It can. Certain dashboard warning lights, such as the airbag, ABS, brake or engine management light, will fail the test if they stay on. Our guide to dashboard warning lights explains which ones matter.