How do I prepare a car for its MOT?
The half hour of owner checks that removes most avoidable failures, what you cannot check yourself, and how the retest rules work.
- Difficulty
- beginner
- Time
- 1 hr
- Read
- 4 min
Short answer
Check every light, the wipers and washers, the horn, the number plates, the tyres, the mirrors and the seatbelts, and top up the screenwash. That covers most of the failures owners can prevent. Anything involving brakes, steering, suspension or emissions is for the tester, not for you.
A car needs its first MOT three years after first registration and then every year. Most failures are not expensive mechanical faults; they are lights, tyres, wipers and things in the driver's view, all of which can be fixed the weekend before for very little.
What you'll need
- Spare bulbs
- Screenwash
- A tyre pressure gauge (optional)
Step by step
- Book early and know the date.You can have the test up to a month minus a day before the current certificate expires and keep the same renewal date. That gives you time to fix anything found without losing days of use.
- Check every exterior light.Sidelights, dipped and main beam, front and rear fog lights, indicators front, rear and side, hazards, brake lights including the high-level one, reversing lights and number plate lights. Lighting is consistently the biggest failure category.
- Check the wipers and washers.Blades that smear or tear will fail, and the washers must actually produce fluid. Both are cheap to sort and both fail cars regularly.
- Look at the windscreen properly.Damage in the area directly swept in front of the driver is assessed against a small size limit, and a larger one elsewhere in the swept area. A chip that has been there for months may be the reason for a failure.
- Check the tyres including the sidewalls.1.6mm minimum across the central three quarters and around the whole circumference, no cuts to the cords, no bulges, correct sizes matched across each axle, and all inflated.
- Test the horn and the seatbelts.Sound the horn. Pull every belt sharply — it should lock — then check for fraying, cuts and that each buckle latches and releases.
- Check the mirrors and the number plates.Mirrors present, secure and unbroken. Plates clean, unbroken, correctly spaced and in the legal font — novelty spacing fails.
- Empty the boot and the cabin.Testers need access to the boot floor and the spare well, and a car full of belongings can hide a fault or simply delay the test.
- Top up the screenwash and check the fuel.Both are needed for the test. A car with almost no fuel cannot be run properly for the emissions check.
- Deal with any warning lights.Airbag, ABS, engine management, brake and tyre pressure monitoring warnings are all failures in their own right. Getting them read beforehand avoids paying for a test that was never going to pass.
- Understand the retest rules.If the car fails and you leave it at the same test centre for repair, the retest is often free within a set period. Taking it away and bringing it back may mean a partial or full fee.
- Read the advisories on the certificate.Advisories are the tester telling you what will fail next year. Acting on them is far cheaper than being surprised twelve months later.
Tips
- You can legally drive to a pre-booked MOT test with an expired certificate, but not for other journeys.
- Give the interior a quick clean. A tester working in a tidy car is a small courtesy that costs nothing.
- Ask the garage to talk you through anything they found. Most will, and it turns the certificate into useful information.
Common mistakes
- Booking on the day the certificate expires — If it fails, the car is off the road immediately and you are dependent on parts availability. Testing a few weeks early keeps the same renewal date and gives you room to fix things.
- Assuming a warning light will be overlooked — Several dashboard warnings are direct failure items. Turning up with one lit usually means paying for a test that had no chance of passing.
If it doesn't work
Failed on emissions
Cause: Faulty sensor, a blocked filter, or simply a cold engine — Fix: Ask what the readings were. Sometimes a good long run beforehand makes the difference; a genuine fault needs diagnosis.
Failed on a headlight aim
Cause: The unit has been disturbed or the car sits differently — Fix: A garage can reset the aim quickly. Check nothing heavy is loaded in the boot during the test.
Failed on a corroded brake pipe or suspension component
Cause: Age and road salt — Fix: This is garage work, not owner work. Get a written quote and, on an older car, weigh it against the car's value.
Failed on a screen chip you had forgotten
Cause: Damage in the driver's swept area exceeds the limit — Fix: Many chips can be repaired rather than replaced, and repairs are often covered by insurance without affecting no-claims.
Questions people ask
When does a car need its first MOT?
Three years after first registration, then every year. Vehicles over forty years old that have not been substantially modified are exempt, though they must still be roadworthy.
Can I drive without a valid MOT?
Only to a pre-booked test, or to a garage for repairs already arranged. Otherwise the car is not legally usable and the insurance position becomes difficult.
What is the difference between a fail and an advisory?
A fail means the car cannot be used until the item is repaired. An advisory is a warning that something is wearing and will likely become a failure, which makes it a useful planning list.