Your MOT is due and you want to give your car the best chance of passing first time. The good news is that most MOT failures are entirely preventable — and the checks that catch them take less than 30 minutes and cost nothing. Here's exactly what to do before your test.
When Should You Prepare?
Ideally start your pre-MOT checks at least one week before your test date. This gives you time to fix anything you find without having to rebook. Leave it the night before and you might find a blown bulb or worn tyre with no time to sort it.
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How much can preparing save you?
A failed MOT costs you the test fee (typically £45–£55) plus a retest fee (around £20–£30) on top of the repair. Catching a blown bulb yourself costs £5. Catching a tyre issue yourself and shopping around saves £30–£60 compared to the garage doing it. Small checks add up to real savings.
The Complete Pre-MOT Preparation Checklist
Work through these checks systematically. Tick each one off as you go — or download our free printable checklist to take with you to the car.
Lights — Most Common MOT Failure
Headlights (main beam)
Switch to full beam and walk in front — both must be working
Headlights (dipped)
Dipped beam on — check both sides are lit and aimed correctly
Brake lights
Press the pedal — reverse near a wall or ask someone to check
Indicators — all four
Check front, rear and side repeaters on both sides
Reverse light
Engage reverse and check the white light at the rear
Number plate light
Often forgotten — switch on sidelights and check the plate is illuminated
Rear fog light
Must work — one or two depending on vehicle age
Hazard lights
All four indicators must flash simultaneously
Tyres
Tread depth — 20p test
Insert a 20p coin into the tread grooves. If the outer band is visible, tread is below 1.6mm — replace before your test
Tyre pressure
Check when cold. Correct pressure is on the door sill sticker or in your handbook
Sidewall condition
Look for bulges, cuts or cracks. Any bulge = immediate replacement needed
Uneven tyre wear
Wear on one edge suggests misalignment — worth flagging to the garage
Windscreen & Wipers
Windscreen condition
Any chip or crack larger than 10mm in the A-zone (directly in front of driver) is a fail. Any crack in the B-zone (rest of swept area) over 40mm is a fail
Wiper blade performance
Run wipers on a wet screen — must clear cleanly without smearing, streaking or skipping
Washer fluid & jets
Screen wash must spray correctly onto the windscreen. Check fluid level and jet direction
Mirrors
All mirrors must be present, undamaged and adjustable. Interior mirror must be secure
Under the Bonnet
Engine oil level
Check dipstick when cold — between MIN and MAX. Low oil can trigger warning lights
Coolant level
Check expansion tank when cold — between MIN and MAX marks
Brake fluid level
Should be between MIN and MAX on the reservoir. Very low level can indicate worn pads
No warning lights on dash
Any warning light that stays on after starting could be a fail — especially the engine management light
Safety Checks
Horn
Press and hold — must produce a continuous tone. Takes two seconds to check
All seatbelts
Pull each belt fully out, check for fraying, make sure buckle clicks and releases cleanly
Handbrake
Should hold car on a hill within 3–4 clicks. Clicking more than 6–7 times before engaging means it needs adjusting
Number plates
Clean, undamaged and correctly spaced. Standard font only — no novelty spacing or styling
What If a Warning Light Is On?
A warning light that stays on after starting your car is a serious concern before an MOT. The engine management light is an automatic major fail — but other warning lights (ABS, TPMS, airbag) can also cause failures depending on what they indicate.
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On the Day of Your MOT
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Make sure you have enough fuel
The tester needs to run the engine during the emissions test. Running out of fuel during your MOT is an embarrassing and avoidable fail. At least a quarter tank is recommended.
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Warm the engine up first
Drive to your MOT rather than getting towed or trailered if possible. A warm engine performs better in the emissions test — a cold start on a diesel can cause higher smoke readings.
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Clear out the boot and back seats
The tester needs clear access to check seatbelts and the spare wheel well. A cluttered car won't fail, but a tester who can't access what they need to check may flag it.
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Bring your V5 and previous MOT certificate
You don't legally need to bring these but they can help if there are any questions about the vehicle. Your MOT history is also available online via the DVSA website.
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Ask for a detailed report regardless of the result
Whether your car passes or fails, ask for the full VT30 or VT32 report showing all advisories. Advisories aren't failures but they tell you what needs attention soon — and can affect the value of your car.
What Are MOT Advisories?
An advisory is a note that something is worn or deteriorating but hasn't yet reached the point of failure. Common advisories include:
- Tyre tread depth approaching the legal limit (e.g. 2mm — legal minimum 1.6mm)
- Brake pads worn to around 3–4mm remaining
- Minor oil leak not yet significant enough to fail
- Suspension components showing early signs of wear
Don't ignore advisories. They are a warning that these items will likely fail at the next MOT — and if the fault worsens, could become a safety issue in the meantime. Use your advisory report as your maintenance to-do list for the year ahead.
Watch out for unscrupulous garages: Some garages add unnecessary advisories to create work for themselves. If an advisory surprises you, get a second opinion before authorising any repair.
Should I Fix Problems Before or After the MOT?
This is the question most drivers ask. The answer depends on what the problem is:
- Obvious failures (blown bulb, worn tyre, cracked windscreen) — fix before. You'll save the retest fee and it's cheaper than the garage doing it as part of a fail-and-repair job
- Unknown fault (warning light, suspected suspension issue) — get a diagnostic first. Know what you're dealing with before committing to a repair. A MotorLoom report for £1.99 tells you the likely cause and cost before you decide what to do
- Suspected major fault — get it checked before the MOT. A car that fails on a dangerous item cannot be driven away — you'll need recovery
Summary
Preparing for an MOT doesn't need to be complicated. Work through the lights, tyres, windscreen, fluid levels and safety checks at least a week before your test. Most checks take under five minutes and the fixes — where needed — are far cheaper done in advance than as an emergency repair after a fail.
If you have a warning light on or a fault you're uncertain about, a MotorLoom diagnostic for £1.99 gives you the likely cause, repair cost and MOT risk assessment before you commit to anything — so you can walk into your MOT with full confidence.
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