CarCostCheck
Maintenance

How to Prepare for Your MOT: 20 Checks That Could Save You Money

A practical checklist of things to inspect before your MOT, based on the most common failure reasons from DVSA data. Catch problems early and avoid expensive retests.

CC
CarCostCheck
8 min read

Quick Answer

40% of cars fail their MOT first time, mostly for simple, fixable issues. Lighting faults, tyres, and brakes account for over half of all failures.

The Most Common MOT Failure Reasons

#1Lighting and signalling
% of Failures: ~18%Typical Fix: Bulb replacement (£5-£15)
View details
#2Suspension
% of Failures: ~13%Typical Fix: Shock absorbers, bushes (£100-£400)
View details
#3Brakes
% of Failures: ~10%Typical Fix: Pads, discs, calipers (£80-£300)
View details
#4Tyres
% of Failures: ~8%Typical Fix: Replacement tyres (£40-£120 each)
View details
#5Driver's view of road
% of Failures: ~7%Typical Fix: Windscreen, wipers (£10-£350)
View details

According to DVSA data, the top five reasons for MOT failure are:

1. Lighting and signalling (around 18% of all failures). Blown bulbs, cracked lenses, incorrectly aimed headlights. 2. Suspension (around 13%). Worn shock absorbers, damaged springs, perished bushes. 3. Brakes (around 10%). Worn pads and discs, seized calipers, corroded brake lines. 4. Tyres (around 8%). Insufficient tread, damage, incorrect size. 5. Driver's view of the road (around 7%). Damaged windscreens, worn wipers, obstructed views.

These five categories account for more than half of all MOT failures. Most can be checked at home without any tools. You can see how your specific car model performs on our reliability rankings page.

Check MOT history free for any of these:

Ford Focus MOT data →Vauxhall Corsa MOT data →Volkswagen Golf MOT data →Ford Fiesta MOT data →BMW 3 Series MOT data →

Check Any Car Free, Instantly

Full MOT history, mileage check, health score, running costs. No signup needed.

GB

Free instant check using official DVSA and DVLA data

🛡️

Buying a used car? Get insurance sorted before you drive it home

Average saving of £504/year

Compare insurance quotes →

Key Takeaways

  • 40% of cars fail their MOT first time, mostly for simple, fixable issues
  • Lighting faults, tyres, and brakes account for over half of all failures
  • Most checks take 15 minutes at home with no tools needed
  • A blown bulb (£5 fix) is the single most common MOT failure
  • Book your MOT in the last month before expiry to maximise flexibility

Around 40% of cars fail their MOT the first time. That is a lot of unnecessary stress, extra garage visits, and repair bills that could have been avoided. Many MOT failures are for simple, fixable issues that any car owner can check at home in 15 minutes. DVSA data shows that lighting faults, tyre issues, and brake problems account for the vast majority of failures. Most of these are easy to spot and cheap to fix before you take the car in.

This is not about gaming the system. It is about catching obvious problems early, fixing them on your terms (rather than at the garage's inflated rates), and avoiding the hassle of a retest. Here are 20 checks you can do yourself, starting with the most common MOT failure reasons.

Lights and Indicators (Checks 1 to 5)

1. Headlights (dipped and main beam)

Turn on your headlights and walk around the car. Both dipped beams and both main beams should work. If one is dimmer than the other or has a yellowish tint, the bulb is likely on its way out. Replace it now. Most headlight bulbs cost £5 to £15 and can be changed in under 10 minutes.

2. Brake lights

Ask someone to press the brake pedal while you check from behind. Both brake lights and the high-level brake light (if fitted) must work. A blown brake light bulb is one of the most common MOT failures and costs under £5 to fix.

3. Indicators

Activate each indicator in turn and check all four corners plus the side repeaters. A fast-flashing indicator usually means a bulb has blown somewhere in that circuit. If your car has LED indicators, a single failed LED within the cluster can cause a failure.

4. Rear fog light and reversing light

At least one rear fog light must work. Reversing lights are not tested on the MOT, but it is worth checking them anyway. Fog light bulbs rarely blow, but the switch or wiring can develop faults, particularly on older cars.

5. Number plate lights

These are easy to forget. The rear number plate must be illuminated by at least one working bulb. Check it at night or in a dark garage. The bulb is usually a small festoon type costing about £2.

Tyres and Wheels (Checks 6 to 9)

6. Tread depth

The legal minimum is 1.6mm across the central three-quarters of the tyre, around its entire circumference. Use a 20p coin: insert it into the tread groove, and if you can see the outer band of the coin, the tread is below 1.6mm. Check all four tyres and the spare (if you have one). Driving on illegal tyres carries a £2,500 fine and 3 penalty points per tyre.

7. Tyre condition

Look for cuts, bulges, cracks, or objects embedded in the tyre. Bulges on the sidewall are particularly dangerous and will cause an instant MOT failure. Run your hand along the inner edge of each tyre (where you cannot easily see) to feel for uneven wear, which might indicate an alignment or suspension problem.

8. Tyre size and type

All tyres on the same axle must be the same size and type. You cannot mix radials and cross-plies on the same axle. Mismatched tyres are a common reason for unexpected MOT failures, especially if the car has had a puncture repair where a different tyre was fitted.

9. Wheel condition

Badly buckled or cracked wheels will fail the MOT. This is more common with alloy wheels, which can crack if they hit a pothole. Spin each wheel and look for visible damage to the rim.

Got a Specific Car in Mind?

Enter any reg below for a free MOT history, mileage check, and running costs. Takes 5 seconds, no signup.

GB

Free instant check using official DVSA and DVLA data

Used by thousands of UK car buyers. Data from DVSA and DVLA.

Brakes (Checks 10 to 12)

10. Brake pads and discs

You can usually see the brake pads through the wheel spokes. The friction material should be at least 3mm thick. If you can see the metal backing plate, they need replacing. Check the brake discs for deep scoring or a pronounced lip at the edge, both of which indicate they are worn and may need replacing.

11. Brake fluid level

Open the bonnet and find the brake fluid reservoir (usually a small, translucent plastic container near the back of the engine bay). The fluid level should be between the MIN and MAX marks. Low fluid is often a sign of worn brake pads, as the pistons extend further to compensate, drawing more fluid into the calipers.

12. Handbrake

The handbrake should hold the car on a slope without needing to be pulled excessively high. If you have to pull it more than halfway up its travel, it may need adjusting. The Ford Focus and Vauxhall Corsa are both known for handbrake cable stretch, which is a simple and cheap adjustment.

Windscreen and Wipers (Checks 13 to 15)

13. Windscreen damage

The MOT allows a maximum chip or crack of 10mm in the driver's "swept area" (the area cleared by the wipers directly in front of the steering wheel). Outside this critical zone, the limit is 40mm. A small chip can often be repaired for free through your insurance. A crack that exceeds the limits will need a full windscreen replacement.

14. Wipers

Worn wiper blades that leave streaks or miss areas of the windscreen will cause a failure. New blades cost £10 to £20 for a pair and take two minutes to fit. Check that the rear wiper works too if your car has one.

15. Washers

Your windscreen washers must produce a jet of fluid that adequately cleans the windscreen. Top up the washer fluid, and check that the nozzles are not blocked (a pin can clear them). It seems trivial, but empty washer fluid is a legitimate MOT failure.

Under the Bonnet (Checks 16 to 18)

16. Engine oil level

While the MOT does not specifically test oil level, a low oil level can cause the engine management light to illuminate, which will cause a failure. Check the dipstick and top up if needed.

17. Emissions warning light

If your engine management light (the amber engine symbol on the dashboard) is illuminated, the car will fail the MOT. This is a relatively recent change that catches many drivers out. Get the fault codes read (most garages will do this for £20 to £30) and fix the issue before the test. Common causes include faulty oxygen sensors, catalytic converter issues, and loose fuel caps.

18. Exhaust

Start the car and listen for blowing or rattling from the exhaust. Walk behind and check for excessive smoke: blue smoke indicates oil burning, black smoke suggests a fuelling problem, and white smoke (beyond initial warm-up condensation) can indicate a head gasket issue. Any of these can cause an emissions failure. The Volkswagen Golf TDI and BMW 3 Series diesel are both models where emissions issues are relatively common in older examples.

Bodywork and Mirrors (Checks 19 to 20)

19. Mirrors

You need at least two functioning mirrors, and one must be the driver's door mirror. Cracked or missing mirrors will fail the MOT. Replacement glass for most models costs £10 to £30 and clips into the existing housing.

20. Bodywork and corrosion

Structural corrosion within 30cm of a load-bearing component (suspension mount, subframe, seatbelt anchor) will fail the MOT. Surface rust on panels is generally fine, but look underneath the car (particularly the sills, wheel arches, and subframe) for anything that looks like it is rusting through. Older Ford Fiestas and Vauxhall Corsas are known for rear wheel arch corrosion.

The Day Before Your MOT

Give the car a basic clean, inside and out. A dirty car does not fail the MOT, but a tester who cannot see a component (because it is caked in mud) may record it as a failure. Make sure the boot is empty so the tester can access the seatbelt mounts. Remove any air fresheners or stickers from the windscreen that might obstruct the driver's view.

If you discover any issues during these checks, you have two options: fix them yourself (lights, wipers, and washers are easy DIY jobs) or take the car to a garage for repair before the MOT. Either way, you will save money compared to discovering the problem during the test, when you will pay for the retest and potentially inflated repair prices.

To see how your specific car compares to the model average, enter the reg plate into our free car checker. You will see its complete MOT history, every advisory ever noted, and a health score based on its track record. For a comprehensive check including stolen, finance, and write-off status, use our full history check.

Want to know which cars are most likely to pass? Browse our reliability rankings or check running costs by model to see how maintenance costs vary across different makes.

Frequently Asked Questions

What are the most common MOT failures?

The most common MOT failure reasons are lighting and signalling faults (18% of failures), suspension issues (13%), brake problems (10%), tyre defects (8%), and driver's view of the road including windscreen damage (7%). Most of these can be checked at home before the test.

Can I check my car before the MOT?

Yes, and you should. Most common MOT failures are for simple issues like blown bulbs, worn wipers, low tread depth, and empty washer fluid. A 15-minute check at home can catch these problems and save you the cost and hassle of a retest.

How much does an MOT retest cost?

If you return the car to the same testing station within 10 working days, a partial retest is often free or costs a reduced fee (typically £10 to £20). If you go to a different station or exceed the 10-day window, you will pay the full MOT fee of £54.85 again.

Will my car fail the MOT with the engine management light on?

Yes. Since 2018, a permanently illuminated engine management light (MIL) is an automatic MOT failure. Get the fault codes read and the issue resolved before your test. Common causes include faulty oxygen sensors, catalytic converter problems, and even a loose fuel cap.

Featured Car Models

Check running costs, MOT data, and reliability for these models.

Ford Focus MOT dataVauxhall Corsa MOT dataVolkswagen Golf MOT dataFord Fiesta MOT dataBMW 3 Series MOT data
Browse all modelsReliability rankings

Related Articles

Reliability

20 Most Reliable Used Cars UK 2026: Real MOT Pass Rate Rankings

10 min read

Running Costs

Cheapest Cars to Run in 2026: Real Data from 19.8 Million MOT Tests

9 min read

Buying Guide

15 Best First Cars for New Drivers UK 2026: Ranked by True Cost

9 min read

Comparison

Petrol vs Diesel in 2026: Which Actually Costs Less to Own?

8 min read

Found a Car You Like? Check Its Full History

Free MOT history, mileage verification, health score, and running costs. Plus optional stolen, finance, and write-off checks for just £4.99.

GB

Free instant check using official DVSA and DVLA data

No signup neededInstant resultsOfficial DVSA data

Reliability Rankings

The most and least reliable cars ranked by MOT pass rate

Running Costs by Model

Browse running cost estimates for every make and model

Cheapest to Run

The cheapest cars to run ranked by real annual costs

GB