Common reasons for MOT test failures and how to avoid them

Common reasons for mot test failures and how to avoid them

No one looks forward to MOT test time, it’s like waiting for your school exam results when all you can do is cross your fingers and hope for that all-important pass instead of a feared MOT failure. Actually, that’s not quite the case, as there are many things you can do and check to avoid your vehicle failing its MOT and you would be surprised at just how simple some of them are. According to VOSA figures, 40% of cars fail their MOT at their first attempt, so even if you are not that worried about your upcoming MOT, maybe you should be…

Here are some of the most common reasons for MOT failures and what you can do to not get caught out by them on your next MOT test.

Lighting and Signalling

Lighting is by far the most common area to cause MOT fails. The DVSA reports that a massive 30% of MOT fails are because of lighting and signalling faults. The solution is simple and cheap, check all your bulbs to make sure they light up when they are supposed to. If any bulbs are out you should replace them before your MOT.

Here’s a list of lights to check:

  • Headlamps (full and dipped)
  • Sidelights
  • Number plate lamps
  • Indicators
  • Hazard lights
  • Brake lights
  • Rear fog lamps

Also watch out for your headlamp aim as if this is off it can also mean an MOT fail.


Braking faults account for over 10% of MOT failures. The most common reason for an MOT fail relating to brakes is excessive wear of the lining of brake pads. Do a visual check on the brake pads for this, including if they are marking the brake discs. Also check for rust and if your brakes are making any noise when applied these could be tell-tale signs of excessive wear. The other common braking fault is if your handbrake doesn’t perform correctly. It should be able to keep the vehicle in place when stopped on a hill, if it doesn’t, or you feel you can pull the lever up too high, you may need to replace of adjust the handbrake cable.

Driver’s View of the Road

MOT failures can be a result of the MOT test finding that the driver’s vision of the road could be obstructed or impaired in specific ways. We’ve already covered lights, but here are some other common reasons:

  • Windscreen – chips over 10mm deep within the driver’s line of sight, or over 40mm within the area covered by wipers mean an MOT fail. Check for any
    chips and get them filled if they are too deep.
  • Wiper blades – 12% of MOT failures are due to faulty wipers. Check the rubber of wiper blades for any wear and splits and also if they smear when it rains. If you suspect there may be too much wear, get them replaced, especially if they are more than a year old, it will likely be cheaper than paying for an MOT retest.
  • Screen wash – top up your screen wash as if you have none it’s a fail. Whilst you’re at it, test your washer jets for any blockages.

Exhaust & Emissions

It’s reported that 7% of MOT failures are down to the exhaust system. This could be because of an unsecured exhaust, worn mounts or holes in the exhaust. Check your exhaust is secure and investigate if it sounds noisy. Fuel system cleaners can flush out carbon deposits and other impurities from your exhaust system and lower your vehicles emissions. Running a fuel cleaner through your car could turn an MOT failure into a pass.


A faulty suspension system is the reason behind 8% of MOT failures. Signs of a faulty suspension include bangs or knocks whilst driving over bumps or the car lurching and bouncing. If this is happening, regardless of whether its MOT season or not, it needs addressing. You can also check if your shock absorbers damp the car correctly by pushing the corner of the car. Once you let go it should return up to its resting height quickly, but if it begins to bounce you may need to replace your shock absorbers before going through with an MOT test.

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