How to prepare for your MOT
Spend twenty minutes the night before checking your lights, tyres, wipers, washer fluid, number plates and horn. Many MOT failures come from these small, free-to-fix items rather than serious mechanical faults.
The MOT can feel like a lottery, but a surprising number of failures come down to things you could have spotted in your own driveway. Blown bulbs, worn wiper blades, an empty washer bottle and dirty number plates all cause fails, and none of them need a mechanic. Setting aside twenty minutes the night before to run through a few checks is the cheapest way to give yourself the best chance of a first-time pass.
Why a few checks the night before pay off
A meaningful chunk of MOT failures are for minor, easily fixed items rather than serious mechanical problems. Many of them are things a driver can see or hear without any tools. Catching them early means you either fix them yourself or arrive knowing about them, which beats a failure, a repair and a return trip. If you want a sense of how long the test itself takes once you get there, our guide on how long an MOT takes sets expectations.
Lights and bulbs
Lighting is one of the most common reasons a car fails, and it is one of the easiest to check. Walk around the car with the ignition on and work through every light: headlights on both dip and full beam, sidelights, indicators front and rear, hazard lights, brake lights, rear fog light and the number plate lights. Brake lights are the classic blind spot because you cannot see them from the driver’s seat, so ask someone to watch while you press the pedal, or back up to a wall or garage door and look for the reflection. A blown bulb is a few pounds and a couple of minutes to replace on most cars.
Number plates and visibility
Number plates must be clean, secure and readable, with the correct spacing and font. A plate caked in mud, cracked, or with novelty spacing can fail. Give both plates a wipe and check they are firmly attached. While you are at the front of the car, make sure your view of the road is not obstructed by stickers, dangling air fresheners or a heavily chipped windscreen in the driver’s line of sight.
Tyres and tread
Tyres are a safety-critical item and a frequent failure point. By law, car tyres must have a tread depth of at least 1.6mm across the central three-quarters of the tread and all the way around the tyre. Below that is both an MOT failure and an offence to drive on. Check each tyre in several places rather than one spot, as tyres often wear unevenly. Look too for cuts, bulges and cracking in the sidewall, and make sure they are inflated to the pressures in your handbook or the sticker inside the driver’s door. A tyre worn close to the limit may only be an advisory today, but it will soon be a fail, so it is worth planning ahead.
Wipers, washers and the windscreen
Your wipers and washers must be able to clear the windscreen properly. Wiper blades that smear, judder or have torn rubber will be marked down, and they are cheap and quick to swap. Top up the washer bottle and test that both the washer jets and the wipers work. An empty washer bottle is a genuine failure point, which feels almost unfair given how easy it is to avoid. Check the windscreen itself for chips or cracks: damage in the driver’s central view above a small size will fail, so get chips seen to before they spread.
Horn, seatbelts and warning lights
Give the horn a quick press to confirm it sounds a clear, continuous note. Check each seatbelt: pull it sharply to confirm it locks, look for fraying or cuts, and make sure the buckles fasten and release cleanly. Finally, turn the ignition on and watch the dashboard. Warning lights that stay lit, such as the airbag, ABS or engine management light, can cause a failure. If one is showing, it is better to get it investigated before the test than to be surprised on the day. Our guide to dashboard warning lights explains what the common ones mean.
A quick under-bonnet and level check
While you are at it, a couple of simple under-bonnet checks are worth a minute. Make sure the engine oil is between the minimum and maximum marks on the dipstick, as very low oil is not good for the car and can hold up an emissions check. Look over the brake fluid and coolant levels too, and glance underneath for any obvious fresh drips on the ground where the car has been parked. None of these guarantees a pass, but a car that is topped up and free of obvious leaks presents better and gives the tester fewer reasons to look harder. It also means that if something is wrong you hear about it from yourself first, on your own timescale, rather than as a surprise at the test centre.
What this does and does not fix
Running through this list will not turn a worn-out car into a healthy one, and it cannot find hidden problems with brakes, suspension or emissions that only a proper inspection reveals. What it does is clear away the easy, avoidable failures so the tester can focus on the parts that genuinely need expert eyes. Think of it as tidying up before an exam rather than a substitute for the exam itself.
If your car does fail on something you could not have spotted, that is not the end of the world. It is worth understanding the common reasons cars fail and, before you book, roughly what an MOT should cost so there are no surprises. A little preparation, though, tips the odds firmly in your favour and often saves you a second trip.
Key takeaways
- A large share of MOT failures are simple items like blown bulbs and worn wipers
- Most pre-checks take minutes and cost nothing, and some faults you can fix yourself
- Car tyres must have at least 1.6mm of tread across the central three-quarters, all the way round
- Preparing beforehand improves your chances of a first-time pass and avoids a retest
Frequently asked questions
Can I really improve my chances of passing myself?
Yes. A meaningful share of failures are for basic items such as bulbs, wipers, washer fluid and number plates, all of which you can check and often fix at home before the test.
How do I check my tyre tread without a gauge?
The edge of a 20p coin works as a rough guide. If the outer band of the coin is hidden when you insert it into the tread groove, you are likely above the limit. A cheap depth gauge gives a proper reading.
Will a dirty car fail its MOT?
Dirt alone will not fail a car, but a tester can refuse to test a vehicle that is too dirty to inspect properly, and mud can hide number plates and lights. A quick wash removes any doubt.
Does topping up screen wash matter for the MOT?
Yes. An empty washer bottle is a genuine MOT failure point because the washers and wipers must be able to clear the windscreen. It takes moments to top up.