What fails an MOT is any item that the Driver and Vehicle Standards Agency (DVSA) standards class as a major or dangerous defect at the time of the test, such as a brake imbalance, a worn tyre, a blown headlamp bulb, a seatbelt that will not latch or an excessive exhaust emission. Minor defects and advisories do not fail the vehicle.
Part of MOT Status & Due Dates. Start with the main guide: MOT Check: Status, Expiry and Test Results
Updated October 2026 · Independent information, not legal advice
The failures people see most often are small, cheap and avoidable, while a few are serious safety problems. Knowing which is which helps you prepare, decide whether to repair first, and understand a result sheet when you receive one. A vehicle's earlier failures are also visible if you check an MOT history before buying or booking.
What Counts As An MOT Fail?
A fail is recorded when the tester finds one or more major defects or dangerous defects. The result sheet lists each one, and the MOT certificate is not issued until a retest passes.
The defect categories
- Dangerous defect: a direct and immediate risk to road safety, so do not drive.
- Major defect: may affect safety or the environment; the test fails.
- Minor defect: no significant effect; the test passes.
- Advisory: something worth watching; the test passes.
Pass with advisories
A pass can include advisories and minor defects. They are noted on the MOT history for future owners.
The MOT Failure List In Outline
A typical MOT failure list groups faults by system, which is the way the tester records them.
- Lights: bulbs out, wrong colour, cracked lenses.
- Brakes: poor efficiency, corroded pipes, worn discs.
- Tyres: low tread, bulges, damage.
- Steering and suspension: excessive play, broken springs.
- Visibility: cracked windscreen, worn wipers.
- Safety: seatbelts, airbag warnings.
- Plates and VIN: damaged or incorrect plates.
- Emissions: failing exhaust readings or smoke.
Why the list is long
Because the test covers many separate items, any one can cause a failure even if the rest of the vehicle is fine.
What Can Fail An MOT On Lights?
Almost any lighting defect can fail a vehicle, which makes this the most common area to check first.
Bulbs and lenses
A blown headlight, brake light, indicator or number plate bulb is a standard failure. A cracked lens that lets water in or alters the beam can also fail.
Aim and colour
Headlights must point correctly and show white or yellowish light, rear lights red and indicators amber. Fitting the wrong colour bulbs fails.
What helps
- Check bulbs with a helper.
- Replace pairs, not singles, where possible.
- Look inside the lamp for condensation or damage.
What Will Fail An MOT On Brakes?
Brakes cause some of the most serious failures because they are critical to safety. The test measures how well the vehicle stops and how evenly.
Efficiency and balance
A brake that is weak or pulls to one side can lead to a major defect. Uneven braking between wheels is a common reason.
Components
- Worn or corroded discs and pads.
- Leaking hydraulic pipes or hoses.
- A parking brake that does not hold.
- Binding brakes that do not release.
Fluid and ABS
Low brake fluid or a lit ABS warning light may also be recorded as a defect.
Tyre Failures
Tyres fail for low tread, damage or incorrect fitment. The legal minimum for cars is 1.6mm across the central three-quarters of the tread.
Common tyre reasons
- Tread below the legal limit.
- Bulges or cuts that show the cord.
- Mixing radial and cross-ply types.
- Tyres rubbing on bodywork.
- Wrong load or speed rating for the vehicle.
Wheels
Loose or missing wheel nuts, cracked alloys and damaged rims can all fail.
Steering And Suspension Failures
Worn components that let the vehicle wander, clunk or feel loose are classed as defects. The tester checks the steering rack, joints, linkages and power steering operation.
Suspension faults
- A leaking shock absorber.
- A broken or corroded spring.
- Worn bushes and ball joints.
- Anti-roll bar links that have snapped.
How it feels
Knocking over bumps, a floaty ride or tyres wearing unevenly all hint at trouble before the test.
Visibility: Windscreen, Wipers, Mirrors
The driver needs a clear forward view, so windscreen damage in the area covered by the wipers can fail a vehicle depending on size and position.
Wipers and washers
Wipers that smear or do not clear the screen, or washers that do not squirt, are quick fails.
Mirrors and tint
Cracked or loose mirrors, and very dark front tint, may also be problems. The rules are on GOV.UK.
Seatbelts And Airbags
A seatbelt that is cut, frayed, missing or will not fasten or release is a fail. Seat mountings must be secure.
- Check every belt, including rear and centre seats.
- A lit airbag warning light can be recorded as a defect.
- Missing airbags or tampered SRS systems can fail.
Number Plate And Identification Failures
Registration plates must be secure, legible and the right colour with correct spacing. A cracked, faded or home-made plate, or characters that have been altered, can fail. See the number plate spacing rules and legal number plates in the UK.
VIN missing or unreadable
The vehicle identification number (VIN) must be present and legible. If it is missing, it can fail.
Exhaust And Emissions
The emissions test measures exhaust gases on petrol and diesel, and checks for excessive visible smoke. A leaking exhaust or a missing catalytic converter or diesel particulate filter can fail.
What affects the reading
A poorly maintained engine, a dirty air filter or a fault shown by an engine warning light can push readings out of limits. See check engine check and CO2 emissions checker.
Body, Structure And Corrosion
Excessive rust in load-bearing areas, sharp edges and insecure panels can fail. Corrosion near suspension mounts or seatbelt anchors matters most.
- Surface rust on a panel is not usually a fail.
- Structural corrosion is.
- A dangling bumper or loose wing mirror may be a fault.
Repairs
Welded repairs must be well made. A bodge can be called out.
Other Equipment That Fails
- A horn that does not work.
- Fuel cap that will not seal.
- Doors that will not latch.
- Bonnet that does not close securely.
- A towbar that is loose or has faulty wiring.
- Missing or damaged mudguards where fitted.
Things people forget
Small items cost little but count the same as big ones on the result.
| Area | Typical cause | Severity example | Usual fix |
|---|---|---|---|
| Lights | Blown bulb | Major | Replace bulb |
| Tyres | Low tread | Major | New tyre |
| Brakes | Worn discs | Major or dangerous | Replace parts |
| Visibility | Worn wipers | Major | New blades |
| Emissions | Dirty filter or fault | Major | Service or repair |
MOT Failures New UK Cars Can Still Face
A new car does not need an MOT until it reaches its third anniversary in Great Britain, so MOT failures on new UK cars are about the first test, not the delivery check. Common causes at that point are tyres and bulbs, plus items affected by use.
Why a young car can still fail
Wear and tear, accident damage or a missed recall can still cause defects even on a three-year-old vehicle.
Failures On Electric And Hybrid Vehicles
The same categories apply, minus exhaust emissions on a pure electric vehicle. Brakes can be affected by lack of use, which causes corrosion on discs, and tyres can wear faster.
- Check brake discs for rust if the car rarely brakes hard.
- Look at tyre condition because of vehicle weight.
- Hybrids keep an emissions test for the engine.
Motorbike Failures
The checks follow the test class for motorcycles. Chains, sprockets, tyres, brakes, lights and steering head bearings are common areas, along with the number plate being secure.
Quick bike checks
Look at chain tension, brake lever feel and lights. See motorbike number plates for plate rules.
What Happens After A Fail
You will be given a failure sheet. If a dangerous defect exists, do not drive the vehicle away unless it is repaired. Otherwise you can usually drive to a repair garage or home if the old certificate is still valid.
Retests
A retest may be free or partial if done within a set period, usually at the same centre. Terms vary, so ask when you book.
Tax and insurance
Failing does not cancel tax. See tax a car without an MOT for how the DVLA treats MOT and tax.
Repair Or Retest: What To Do First
Sort the failure sheet into quick fixes you can do yourself, such as bulbs and wiper blades, and safety work that needs a qualified mechanic, such as brakes and steering. Do the dangerous items first and keep receipts so the retest centre can see the work.
Getting a fair quote
- Ask for the failure items in writing.
- Compare quotes for the same list of work, not just a headline figure.
- Ask whether parts are new, used or remanufactured.
- Check the repair garage is happy to retest or can return the car to the original centre.
Time limits matter
A retest at the same centre is often only free or partial within a set window, so do not leave the repairs for weeks. The centre sets the terms and GOV.UK describes the rules.
Vans, Company Cars And Fleets
Vans and company vehicles fail for the same reasons, but they cover more miles, so tyres, brakes and lights wear faster. A fleet manager should schedule checks inside the early test window so there is time to repair and retest before the MOT expiry date; see change MOT date for how that window works.
- Check load-bearing areas and rear doors on vans.
- Log defects between tests to catch repeat faults.
- Keep drivers reporting bulbs and tyre damage promptly.
Check An MOT History For Past Failures
You can check an MOT history by entering the registration into the free number plate check or the MOT check service. The record shows failed tests, advisories and mileage at each visit.
Reading the pattern
Repeated failures on the same item can mean a poor repair. A long gap between tests can mean the car was off the road.
Buying A Used Car: Failures To Look For
A car that failed repeatedly, or only just passed with long advisory lists, can be a warning sign. Compare the recorded mileage at each test with the odometer, using mileage check, and read what to look for when buying a used car.
Questions for the seller
- When was the last fail, and what was repaired?
- Are there old advisories that were never fixed?
- Who did the repair work, and is there an invoice?
What Does Not Fail An MOT
Things that look bad but do not fail include minor paintwork scratches, interior wear, a dirty car, an engine that is noisy but within limits, and service history.
- A service light alone is not an MOT item.
- Cosmetic damage not affecting safety is usually fine.
- Missing floor mats are not a fail.
Northern Ireland Failures
In Northern Ireland, tests are run by the DVA. Many of the same faults apply, but the booking process and test regime differ. Read MOT in Northern Ireland.
Ten Fast Checks Before You Book
- Bulbs and lenses.
- Number plates.
- Wipers and washer fluid.
- Tyre tread and sidewalls.
- Horn.
- Seatbelts.
- Mirrors.
- Brake feel.
- Fluid leaks.
- Warning lights.
Common Mistakes
- Waiting for the test to discover a blown bulb.
- Ignoring a chip that has spread into a crack.
- Assuming a previous pass guarantees the next.
- Fitting cheap parts that do not meet the standard.
Myth: failing means the car is unsafe to drive home
Not always. Only a dangerous defect means you should not drive. For other fails, check the rules on GOV.UK.
Frequently Asked Questions
What fails an MOT most often?
Lights, tyres, brakes and visibility items such as wipers cause a large share of failures, based on how often these items appear on result sheets. They are also the cheapest to fix. Check bulbs, tread, wiper blades and brake feel before you book to avoid a pointless failure.
What can fail an MOT without me noticing?
Plenty. A rear number plate lamp that has blown, a sagging brake pipe, worn suspension bushes, a cracked light lens or a washer jet that does not work are all easy to miss. A helper walking around the vehicle while you test the controls will catch most of them.
What will fail an MOT immediately?
A dangerous defect leads to an automatic failure and you should not drive the vehicle. Examples include severe brake faults, a tyre with exposed cord or a steering component close to breaking. A major defect also fails the test. A minor defect or an advisory does not.
Is there an official MOT failure list?
The DVSA publishes the inspection manual that sets the standards, and test centres follow it. There is no single short list because the test covers many systems. A practical MOT failure list is grouped by area: lights, brakes, tyres, steering, suspension, visibility, seatbelts, plates, emissions and body.
Can a warning light fail an MOT?
It can. A lit airbag, ABS or electronic stability warning may count as a defect, and an engine management light can fail if it points to an emissions fault. Other lights may be advisories. Getting a warning light diagnosed before the test is cheaper than a failed test and retest.
Do advisories mean I failed?
No. An advisory is a note about something that may become a problem soon, such as worn tyres approaching the limit. The vehicle passes. Treat advisories as a repair list for the next few months because they can become major defects at the following test.
Can a new car fail an MOT?
A car does not normally need an MOT until its third anniversary of first registration in Great Britain. At that first test it can fail like any other, for example because of tyres, bulbs or accident damage. MOT failures on new UK cars are usually minor and inexpensive to fix.
Can I drive after an MOT fail?
It depends. If the old certificate is still in date and there is no dangerous defect, you can usually carry on driving, as long as the vehicle is roadworthy. If the certificate has expired, you may only drive to a pre-booked retest or repair. A dangerous defect means do not drive it. Check GOV.UK.
How can I see why a car failed before?
Enter the registration into the free number plate check or the official GOV.UK service to check an MOT history. It lists each test, whether it passed or failed, and the defects or advisories recorded. That helps you spot repeated problems before you buy or book a test.
Are MOT failures different in Northern Ireland?
The test is run by the DVA and many of the same items apply, but the procedures, first-test age and booking differ. Check nidirect for current rules. Failure details from Northern Ireland tests are not normally shown in Great Britain MOT history lookups.
What is the difference between an MOT test and a roadworthiness check?
The MOT test is the annual inspection of a vehicle's roadworthiness at the time of the test only. It is not a service and does not cover the engine or gearbox condition. Older paper certificates had form numbers such as VT20 for a pass, but results are now recorded electronically. See GOV.UK for the current wording.
Official Sources
Rules, fees and deadlines change. Confirm anything that affects your money or legal position with the official service.