Your MOT test covers all major areas of your vehicle, from brakes and tyres to lights, steering, and emissions. If you're not sure what gets checked during an MOT, you're not alone. The tester checks each component against pass thresholds, and you can spot potential failures before your appointment.
What the MOT test actually covers
The MOT test is a legally required annual inspection for most UK vehicles from their 3rd year of registration, checking that your car meets minimum road safety and environmental standards. It does not cover the engine, clutch, or gearbox.
The inspection covers these major categories:
- Vehicle identification
- Brake system checks
- Steering checks
- Visibility checks
- Lights, reflectors and electrical equipment
- Axles, wheels, tyres and suspension
- Body, structure and attachments
- Seatbelts and safety equipment
- Exhaust emissions, fuel system, noise and fluid leaks
Results fall into 3 tiers: Minor (pass, repair soon), Major (fail — fix before driving), or Dangerous (must not be driven until repaired). Brake fluid is checked visually through the reservoir; DVSA rules prohibit removing the cap.
1. Vehicle identification
Registration plates and the vehicle identification number (VIN) both get a quick check during the MOT. Your plates must be clean and legible from 20 metres, use the correct UK font (Charles Wright 2001), have proper character spacing, display white at the front and yellow at the rear, and carry working rear illumination. Plate failures account for 0.9% of all MOT failures, easy to avoid with a wipe-down before your test. The tester also confirms your VIN matches the vehicle registration on the test record.
2. Brake system checks
Brakes are tested on a rolling road that measures both efficiency and balance. Your service brake must hit at least 58% efficiency; the parking brake must reach 16%. If either side of an axle shows more than 30% imbalance, the car fails.
Testers inspect:
- The pedal
- Servo
- Pipes
- Hoses
- Discs
- Pads
- Calipers
- Master cylinder
Brake pads worn below 1.5mm trigger a Major defect. Brake fluid is checked visually through the transparent reservoir only, caps stay on; a low or contaminated level fails. ABS and ESC warning lights must be extinguished after startup.
3. Steering checks
The steering system covers:
- The steering wheel
- Column
- Rack and pinion
- Gaiters
- Track rod ends
- Power steering components
Testers check for excessive free play, wear, and damage throughout. Steering accounts for around 3% of MOT failures, but any significant looseness in the column or worn track rod ends will earn a Major defect.
Power steering fluid level is checked, and the electronic power steering warning light must extinguish after startup. If it stays on, that's a failure.
4. Visibility checks
Visibility checks cover 5 components:
- The windscreen and glazing
- Driver's field of vision
- Wipers and washers
- Mirrors
- The bonnet catch
The windscreen uses zone-based damage thresholds. Zone A — a 290mm band directly in front of the driver, allows damage no larger than 10mm. Elsewhere in the wiper-swept area, the limit rises to 40mm. Wipers must clear the screen effectively and washers must produce fluid. All mirrors, including interior and exterior, must be secure and functional. The bonnet catch must hold the bonnet firmly closed while driving.
5. Lights, reflectors and electrical equipment
Lights and signals cause more MOT failures than any other category — 29.6% of all failures, according to DVSA data. Every exterior lamp gets checked:
- Headlights (dipped and main beam, including beam alignment to prevent dazzling)
- Side lights
- Tail lights
- Brake lights
- Indicators
- Hazard lights
- Rear fog lamps
- Reversing lights on vehicles registered after 2009
- Daytime-running lights
- Number plate illumination
Reflectors are inspected too, as are dashboard warning tell-tales, which must illuminate at startup. The battery must be secure and free from leaks, visible wiring must be intact, and any trailer electrical socket is checked. A single faulty bulb fails the test.
6. Axles, wheels, tyres and suspension
Tyres and suspension together account for over 30% of all MOT failures, making them the 2 most critical areas to check beforehand.
Tyres are inspected for:
- A minimum tread depth of 1.6mm across the central three-quarters of the tread width around the entire circumference
- Cuts
- Bulges
- Exposed cords
- Matching construction type on the same axle
- The TPMS warning light on vehicles registered after 2012
Insert a 20p coin into the groove, if the outer band stays visible, the tread is too low.
The suspension check covers:
- Shock absorbers
- Springs
- Bushes
- Anti-roll bars
- Ball joints
- Wheel bearings
- Mounting points
Suspension failures account for 20.2% of all MOT failures.
7. Body, structure and attachments
The MOT's body and structure check covers:
- Corrosion
- Panel security
- Mechanical attachments throughout the vehicle
Inspectors look for sharp edges from rust or collision damage, these are an automatic failure. Corrosion within 30cm of load-bearing, steering, or suspension components also fails the test, even if the car feels solid to drive.
The following are all checked for security and damage:
- Doors
- Catches
- Hinges
- Seats
- Seat backs
- The boot
- Tailgate
- Bumpers
Towbars and coupling equipment are inspected if fitted. Engine mountings are assessed. Fuel leaks, detected by smell of petrol or visible dripping, are an immediate failure.
8. Seatbelts and other safety equipment
Seatbelts and safety equipment cover 7 distinct checks.
All fitted seatbelts must:
- Be in good condition
- Latch securely
- Lock properly through the inertia-reel mechanism
- Retract fully
- Have anchor points free of serious corrosion
The airbag/SRS warning light must illuminate at startup then extinguish; if it stays lit, that's a Major defect and an automatic fail.
The following are also checked:
- The horn
- The speedometer
- Electronic stability control (ESC) warning lights
- Anti-theft equipment
Your horn must produce a continuous, uniform note audible to other road users, novelty multi-note horns are specifically prohibited. The speedometer must work and illuminate (cracked glass is acceptable if the speed remains readable). Electronic stability control (ESC) warning lights must also extinguish at startup, and anti-theft equipment is inspected.
9. Exhaust emissions, fuel system, noise and fluid leaks
Exhaust and emissions testing varies by fuel type. Petrol vehicles are tested for CO and HC levels against legal limits. Diesel vehicles undergo a smoke opacity test, any visible smoke of any colour is a Major defect and an automatic failure.
The catalytic converter must be present if your car originally had one. A missing or tampered converter is a Major defect and fails the test immediately. The diesel particulate filter (DPF) status is also checked.
Your engine management warning light must illuminate at startup and then extinguish. Excessive exhaust noise fails the test, as do testable fluid leaks. From 2025, EVs face additional checks covering battery health, high-voltage wiring, and charging systems.
What's NOT Checked During an MOT
The MOT test checks safety and emissions compliance and it does not assess your car's general mechanical health.
The DVSA explicitly excludes:
- The condition of the engine
- The clutch
- The gearbox
- The spare tyre itself
- Tyre repair kits
- Components that would require dismantling to inspect
Your car can pass its MOT with a worn clutch or a noisy gearbox, and the tester will not flag any of it.
The spare wheel is not inspected either. Run-flat tyres and tyre repair kits fall outside the test scope too.
Most people assume a passed MOT means the car is fully serviced and mechanically sound. It doesn't. The MOT is a minimum safety and environmental standards check.
How to prepare your car for an MOT
Start your pre-MOT checks 1 to 2 weeks before the test date, that gives you time to fix anything you find.
Work through this checklist:
- Lights — test every light: headlights, indicators, brake lights, tail lights, fog lights, and reversing lights. Lights account for 29.6% of all MOT failures, so start here.
- Tyres, insert a 20p coin into the tread grooves. If the outer band is visible, your tread is below the 1.6mm minimum.
- Brakes, press the pedal firmly. A soft or spongy feel signals a problem.
- Windscreen, check for chips or cracks in the driver's line of sight.
- Wipers and washers, blades must clear the screen; washers must produce fluid.
- Seatbelts, pull each belt firmly to confirm the inertia reel locks and the buckle latches cleanly.
- Horn, one press confirms a clear, continuous note.
- Fluid levels, top up engine oil, coolant, and washer fluid.
The test itself takes 45 to 60 minutes. There is no grace period once your certificate expires, driving without a valid MOT carries a fine of up to £1,000, 6 penalty points, and police can seize the vehicle.
From 2025, MOT testers photograph your car during the inspection and upload the images to the DVSA record to prevent fraudulent certificates being issued for cars never tested.
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