What fails an MOT? Common failures, rules and practical checks
Written by the Point S UK technical team — tyre and autocare specialists operating 400 fitting centres across the UK. Last reviewed: September 2026.
The most common reasons a car fails its MOT are faults with lights and signalling (nearly 30% of all defects), suspension (20%), and brakes (17%), according to DVSA data. Tyres, windscreen damage, and exhaust emissions follow closely behind.
Around one in three vehicles fail their initial MOT test each year in the UK — but most failures are avoidable with the right preparation. This guide covers the most common failure reasons, defect categories, what happens if your car fails, and a practical checklist to help you pass first time.
At a glance: the most common MOT failures
| Failure category | % of defects | Most common issue |
|---|---|---|
| Lights & signalling | 29.6% | Blown bulb or misaligned headlights |
| Suspension | 20.2% | Worn shock absorbers or coil springs |
| Brakes | 17.2% | Worn pads/discs or failing parking brake |
| Tyres | 10.4% | Tread below 1.6 mm (also 60% of dangerous defects) |
| Driver's view | 8.7% | Windscreen chips >10 mm or torn wiper blades |
| Fuel & exhaust | 5.4% | Exhaust leaks or excessive emissions |
| Steering | 3.0% | Excessive play, leaking power steering fluid |
Source: DVSA MOT data
What can cause your MOT to fail?
Lighting and signalling faults
A blown bulb is the single most common cause of MOT failure in the UK. Testers check every lamp on your vehicle — headlights, brake lights, indicators, fog lights, and registration plate lamps. Faulty headlights or misaligned beams result in an immediate major defect. Walk around your car and check every bulb before your test.
Brake faults
Braking systems account for 17.2% of all MOT defects. Testers examine brake pad and disc wear, brake pipe corrosion, parking brake effectiveness, and whether the ABS warning light illuminates. They also check the brake servo, master cylinder, and calipers. A parking brake that fails to hold the car on a slope is an immediate fail, as are leaking brake fluid lines or heavily corroded brake pipes.
Tyre faults
Tyres account for 10.4% of all MOT defects but represent nearly 60% of all dangerous defects. Tread depth must be at least 1.6 mm across the central three-quarters in a continuous band around the entire circumference. Visible damage such as cuts, bulges, or exposed cords — and an incorrect tyre type for the axle — are also automatic failures. If you notice signs of excessive tread wear or sidewall deterioration before your inspection, ask your local Point S experts to find the correct replacement tyres and avoid an avoidable MOT fail.
Suspension faults
Suspension accounts for 20.2% of initial MOT failures. Shock absorbers, coil springs, suspension arms, ball joints, and bushes are all inspected for wear and corrosion. Signs of an MOT issue include a bouncy ride, knocking sounds, or the car pulling to one side.
Steering faults
Steering accounts for 3% of MOT defects but frequently results in dangerous classifications. The tester checks for excessive play in the steering wheel, worn rack components, and leaking power steering fluid. If your steering feels vague, have it inspected before your test.
Windscreen, emissions and bodywork issues
Your windscreen will fail if chips or cracks compromise the driver's field of vision — damage over 10mm within the wiper-swept area is an automatic failure. Torn wiper blades and non-functioning windscreen washers also cause failure.
Emissions testing checks exhaust integrity and whether your vehicle meets environmental standards. Bodywork is scrutinised for structural rust near safety-critical areas, sharp edges, and corrosion around mounting points. Seat belts and airbag warning lights are also assessed.
Mirrors, horn and other common failures
Several other components are checked that drivers often overlook:
- Mirrors: All interior and exterior mirrors must be intact and secure. Cracked or missing mirrors are a fail; minor chips that don't affect visibility are advisories.
- Horn: Must produce a loud, audible sound. A non-functioning horn is a major defect; novelty musical horns are not permitted.
- Number plates: Must be clean, legible, and correctly formatted. A missing plate light is also a fail point.
- Dashboard warning lights: Any lit warning light for a safety-critical system — ABS, airbags, ESC, engine management, or TPMS (since 2015) — results in automatic failure.
MOT defect categories: minor, major and dangerous
Since May 2018, the UK MOT test uses a three-tier defect system. Minor defects are listed as advisories on your VT30 certificate — the car still passes. Major defects result in immediate MOT failure. A single major defect is enough to fail; minor defects noted on the VT30 should be monitored as they can worsen into major faults before your next test.
| Category | Definition | MOT result | Can you drive away? |
|---|---|---|---|
| Minor | Defect with no significant effect on vehicle safety | Pass (advisory note) | Yes |
| Major | Defect that may affect vehicle safety or environmental impact | Fail | Only if previous MOT still valid |
| Dangerous | Direct and immediate risk to road safety or serious environmental impact | Fail | No – illegal to drive |
Pre-MOT preparation: practical checklist to pass your UK MOT test
A few simple checks before your annual MOT can help you avoid common problems and save time:
- Lights: Check all bulbs are working, including headlights, indicators and brake lights
- Tyres: Ensure tread depth is above the legal 1.6 mm limit across the central three-quarters of each tyre (a 20p coin test works well). Also check that your TPMS (Tyre Pressure Monitoring System) warning light is not illuminated — since 2015, a lit TPMS light is an automatic MOT failure
- Windscreen: Look for significant chips in the driver's field of vision and check wiper blades are in good condition with washer fluid topped up
- Number plates: Verify they're clean and legible
- Basic functions: Test your horn, check mirrors are secure, and ensure there's no excessive play in the steering
Before your test date, consider booking a professional pre-MOT inspection at a reputable garage—for detailed guidance, see our full pre-MOT check guide.
Frequently asked questions
Can I drive my car away if it fails an MOT?
Yes, you can take your car away if the faults are not classed as "dangerous" and your previous MOT is still valid. However, if a "dangerous" defect is found, it is illegal to drive the vehicle. You must have it repaired or towed to another garage for fixes.
Do I have to pay for my MOT again if it fails?
A completely free retest only applies if your vehicle remains at the test centre for repair and retesting within 10 working days, or if you take it away and return it before the end of the next working day for specific items to be rechecked (such as windscreen wipers, mirrors, or tyres). If you take the vehicle away to carry out the required repairs elsewhere and return it within the 10 working day window, you will not have to pay the full price again; instead, you qualify for a partial MOT retest at a reduced fee (typically up to half the standard test rate). Should you return after 10 working days, a full test fee will be charged.
How long do I have to fix a failed MOT?
You have 10 working days from the initial failure to return to the original test centre for an MOT retest at a free or reduced rate. While there is no statutory deadline requiring you to complete necessary repairs within a set timeframe, you cannot legally drive on public roads once your existing MOT certificate expires, unless travelling directly to a pre-booked repair or test appointment.
How long does an MOT test take?
An MOT test typically takes 45 minutes to an hour for a standard car. If the tester identifies issues during the inspection, or if repairs are carried out on the same day, the process will take longer.
Will my car fail MOT if the tyre pressure light is on?
Yes, if your car was first used on or after 1 January 2012. An illuminated Tyre Pressure Monitoring System (TPMS) warning light that signals a system malfunction is categorised as a major defect, resulting in an automatic MOT failure. Always check pressures and reset the system beforehand.
Is an oil leak or minor defect an MOT failure?
No, a minor defect or slight oil seep will not fail an MOT; your car still passes, but the issue is recorded on your certificate. However, an excessive oil leak that drips continuously, creates a pool over 75 mm, or contaminates brakes is classed as a major or dangerous defect, resulting in failure.
How much does an MOT cost?
The maximum fee for a car MOT is £54.85 (as set by the government — garages can charge less but not more). For motorcycles, the maximum is £29.65. Repair costs are always separate from the test fee itself.
Ready to book your annual inspection? Find your local Point S centre and book your MOT today for expert servicing, transparent pricing, and complete peace of mind.
