Lighting defects contribute to 19m+ MOT failures since 2020
Minor lighting faults can be a big issue for your MOT - but they're often preventable
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Lighting defects have contributed to more than 19 million MOT failures since 2020, according to our new research.
A Freedom of Information (FOI) request we submitted to the Driver and Vehicle Standards Agency (DVSA) revealed that over 3.4 million lighting-related faults are recorded every year.
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The worst year for lighting defects (2020 – 2024)
The data reveals 2021 as the worst year for lighting defects, with over 3.5 million contributing to MOT failures. Over 3.4 million defects were recorded in 2023 and 2024, indicating a small improvement since 2021. With 1,964,738 defects recorded for 2025 to date (as of August 2025), this year’s final numbers look set to finish up in a similar position.
2021: 3,515,710 defects (highest year)
2023: 3,480,956
2020: 3,477,625
2022: 3,477,540
2024: 3,468,614
The top 5 lighting defects recorded during MOTs
Lights ‘not working’ was the most common fault between 2020 and 2025, with 7.2 million recorded instances.
Not working: 7,205,285
Projected beam image is obviously incorrect: 1,877,732
Not working on dipped beam: 1,781,560
Inoperative in the case of a single lamp or all lamps: 1,500,636
Too low: 1,006,788
These figures highlight a large volume of low-tech issues that drivers could identify themselves through basic visual checks before their MOT.
Ben Welham, our motoring expert, said: “Our research shows that minor lighting faults contribute to millions of MOT failures each year.
"The good news is that these are usually easy to spot and fix before your MOT, such as replacing a bulb or checking headlight alignment, helping drivers avoid extra costs and stay safe on the road.”
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Headlight alignment issues: “too low” vs. “too high”
Headlights that are ‘too low’ (1 million) are 60% more common as major defects in an MOT than headlights that are ‘too high’ (621,000). Motorists are around 60% more likely to fail an MOT because their headlamps are aimed too low rather than too high, with 1,006,788 "too low" defects compared to 621,281 "too high" defects.
This finding highlights a hidden safety risk, with low-aimed beams potentially reducing drivers’ visibility, often without them realising it.
Ben said: “It’s trickier to tell when your headlight alignment is too low or high than if the bulbs aren’t working, which is why it’s an important check in an MOT.
“The alignment can change over time due to factors such as suspension sagging with age, vibrations from everyday driving, changing your bulbs or even issues with auto-levelling systems. It can also depend on if your tyres are at the right pressure, how much fuel is in the car and if you have anything heavy in the boot.
“It’s possible to adjust your headlight alignment yourself by parking in front of a wall, measuring the light pattern and using the adjustment screws – but it’s a bit involved. Garages have a special tool to make things easier if you’re not confident doing so yourself.”
Simple checks could prevent millions of MOT failures
Ahead of an MOT, Ben offers drivers some advice to help identify lighting faults, saying: “Walk around your Mercedes with all lights turned on, including indicators, brake lights (you might need to ask someone to help with this), high/main and dipped beams, and hazards. In less than a few minutes you can understand whether your car’s lighting works properly or not.
“If you’re not sure about your headlight alignment and want to get it checked at a garage, it’ll usually cost less than £20 and only take a few minutes – worth it to avoid the hassle of retaking your MOT.
“MOT tests are rigorous with lighting checks because they’re so important for safety. So, it’s still worth giving your lights a check or taking your car into a garage if you’re worried that your lights aren’t up to scratch – whether your MOT is due soon or not.”
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