MOT Failures Explained: Common Reasons and How to Avoid Them
An MOT failure can be frustrating, inconvenient, and sometimes expensive. At Auto MOT Centre in Manor Park, London E12, we test hundreds of vehicles every week, and while many pass first time, others need minor repairs first. Understanding why cars fail their MOT helps you prepare better and potentially avoid the stress of a retest. This guide explains the most common MOT failure reasons and what you can do about them.
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Understanding the MOT Test
The MOT test checks your vehicle meets minimum safety and environmental standards. It is not a comprehensive health check—just the minimum required by law for roadworthiness. The test covers:
Body and structure – General condition and corrosion
Brakes – Function and condition
Lights – All lights and signals
Steering and suspension – Condition and operation
Tyres and wheels – Condition, size, and tread depth
Exhaust and emissions – Noise levels and pollutant output
Windscreen and mirrors – Visibility and condition
Seat belts – Operation and condition
Registration plate – Visibility and format
Fuel system – No leaks or damage
Noise – Exhaust sound levels
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Top 10 Reasons for MOT Failure
Based on our testing data at Auto MOT Centre, here are the most common reasons vehicles fail:
1. Lighting and Signalling (18% of failures)
What gets tested:
All bulbs working and correctly positioned
Headlights aim correctly
Brake lights activate with brake pedal
Indicators flash at correct rate
Common issues:
Bulbs blown (especially brake lights)
Failed headlight aim (too high or too low)
Side indicators not working
How to avoid:
Walk around your car weekly checking all lights
Replace any blown bulbs immediately
If headlights seem misaligned, get them adjusted
2. Tyres (14% of failures)
What gets tested:
Tread depth minimum 1.6mm across central 75%
No damage, cracks, or bulges
Correct tyre size for the vehicle
Spare tyre (if fitted)
Common issues:
Tread below minimum depth
Damage from kerbs or potholes
Incorrect tyre pressure
Mixing tyre types without approval
How to avoid:
Check tyre pressure monthly
Inspect for visible damage regularly
Replace tyres before they reach minimum tread
At Auto MOT Centre, we check tyres during every service
3. Suspension (12% of failures)
What gets tested:
Shock absorbers (must function correctly)
Springs (no broken leaves or coils)
Suspension joints and bushes
Steering components
Common issues:
Worn shock absorbers (bouncy ride)
Broken or sagging springs
Clunking from suspension
Leaking struts
How to avoid:
Watch for bouncy ride or handling issues
Avoid potholes and kerb impacts where possible
Have suspension checked during services
Replace worn components before they fail MOT
4. Brakes (10% of failures)
What gets tested:
Brake pads and shoes (sufficient material)
Brake discs and drums (not worn thin)
Brake hoses (no cracks or leaks)
Handbrake holds on incline
No pulling to one side
Common issues:
Worn brake pads (below minimum thickness)
Worn brake discs
Sticking brake calliper
Faulty brake light switch
Handbrake out of adjustment
How to avoid:
Do not ignore squeaky brakes
Check for pulling when braking
Have brakes inspected regularly
Replace worn components before they fail
5. Emissions (8% of failures)
What gets tested:
Exhaust smoke levels
CO and HC emissions (petrol)
Opacity levels (diesel)
Catalytic converter function
Lambda sensor operation
Common issues:
Engine management light on
Rich or lean running
Faulty lambda sensor
Failing catalytic converter
Excessive oil consumption
How to avoid:
Address check engine light immediately
Service your engine regularly
Use quality fuel
Have emissions checked before MOT if concerned
6. Windscreen (6% of failures)
What gets tested:
No cracks in driver’s line of sight
Chips larger than 10mm outside vision area
Wipers leave clear vision
Washer provides adequate wash
Common issues:
Stone chips in driver’s view
Cracks from temperature changes
Worn wiper blades leaving streaks
Empty washer bottle
How to avoid:
Repair stone chips promptly
Replace wiper blades annually
Keep washer fluid topped up
Do not use wipers on frozen glass
7. Steering (5% of failures)
What gets tested:
Steering wheel condition
Steering box and rack
Steering joints and linkages
Power steering system
Common issues:
Excessive play in steering
Leaking power steering fluid
Worn steering components
Damaged steering rack gaiters
How to avoid:
Watch for play in steering or strange handling
Check power steering fluid regularly
Avoid hitting kerbs and potholes
Have steering checked during services
8. Mirrors, Wipers, and Washers (4% of failures)
What gets tested:
All mirrors present and undamaged
Wipers clean the screen adequately
Washers provide washer fluid
No missing mirrors or broken wiper arms
How to avoid:
Replace worn wiper blades
Keep washer bottle full
Check mirrors for cracks or looseness
9. Body and Structure (3% of failures)
What gets tested:
No excessive corrosion
No sharp edges
Doors open and close properly
Boot and bonnet catch working
How to avoid:
Wash car regularly to remove road salt
Touch up stone chips promptly
Check for rust spots, especially wheel arches
Ensure all doors close properly
10. Registration Plate (2% of failures)
What gets tested:
Clearly readable
Correct format and spacing
Securely attached
Clean and undamaged
How to avoid:
Clean number plates regularly
Replace if damaged or faded
Ensure both front and rear plates are attached
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What Happens If Your Car Fails?
At Auto MOT Centre, when your car fails:
We explain every failure – You receive a clear written report
We provide a quote – See exactly what repairs cost before agreeing
We can often fix issues same day – Many minor repairs we can complete while you wait
Free retest if we repair – If we do the work, the retest is often free
The key is not to panic—many failures are simple to fix.
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How to Improve Your Chances of Passing
Before Your MOT
Use our pre-MOT check – We can identify issues before the test
Check lights yourself – Replace any blown bulbs
Check tyre tread – Replace if close to minimum
Check windscreen – Repair any chips in driver view
Check wiper blades – Replace if they streak
Top up fluids – Oil, coolant, screen wash
Book Early
Book your MOT before it expires
If it does expire, you cannot drive to the test (must be towed or recovered)
Give yourself time for any repairs if needed
Choose a Quality Garage
At Auto MOT Centre:
We use quality parts for repairs
Our mechanics are experienced and trained
We explain issues clearly
We offer fair, transparent pricing
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Book Your MOT at Auto MOT Centre
Do not risk driving with an expired MOT or failing unexpectedly. Book your test at Auto MOT Centre in Manor Park.
