MOT defect file
Stop lamp not working
Last updated
Quick answer
A brake light is out. It is a straightforward fix, but it removes the main warning you give a following driver, so it is treated as a failure rather than an advisory.
- Typical cost
- £5–£70
- DIY viability
- Straightforward
What you might notice
- Almost never noticed from inside the car, since nothing on the dashboard reports it
- On some models a bulb failure warning appears in the instrument display
- Both stop lamps dead at once, which points at the pedal switch rather than the bulbs
- Brake lights that stay on permanently, or come on with the ignition alone
What causes it
- A blown bulb — and because both sides see identical use, the second often fails soon after the first
- A failed brake pedal switch, which explains both lamps going out together
- Corrosion in the holder or a broken earth path, common on older estates and hatchbacks
- A misadjusted pedal switch, which instead leaves the lamps permanently lit
Advisory or failure?
A stop lamp that does not work is a major defect. Vehicles first used from 1 April 1980 need at least two working stop lamps, so one dead lamp on a pair is a failure. A high-level third lamp fitted as original equipment must also work. A lamp that is noticeably dimmer than its pair, or shows through a cracked lens with reduced intensity, can be recorded as either minor or major depending on how far it falls short.
Can you fix it yourself?
Straightforward
Rear bulbs are usually reachable through a panel in the boot trim or by releasing the whole lamp cluster on two screws. The only awkward part is doing it single-handed: park facing a reflective surface, or wedge something against the pedal so you can see the result. If both lamps are out, test the pedal switch before buying bulbs — it is a cheap part but sits up in the pedal box and is more fiddly than a bulb change.
What it costs
The bulb itself is usually £3 to £8 for a pair, and the job is fifteen minutes. A garage will typically charge £20 to £35. A brake pedal switch is £10 to £25 for the part but takes longer to reach, so budget £50 to £70 fitted. Sealed LED clusters on newer cars are the expensive case and can exceed the top of this band on their own.
What happens if you ignore it
This is the defect most likely to cause a rear-end collision, because the only warning a following driver gets is the one that is missing. In a claim, defective brake lights make contributory negligence straightforward to argue against you. It is also an offence to use the vehicle in that condition, and unlike most faults, other drivers can see it and report it.
Common questions
- Is a brake light out an MOT failure?
- Yes. Vehicles first used from 1 April 1980 must have at least two working stop lamps, so one dead lamp of a pair is a major defect and a failure. A high-level third brake light counts too if it was fitted as original equipment. A lamp that works but is noticeably dimmer than its pair may be recorded as minor or major depending on how far short it falls.
- How do I check my own brake lights alone?
- Reverse up to a window, garage door or shop front at dusk and press the pedal while watching the reflection. Failing that, wedge something heavy against the brake pedal so it stays pressed, then walk round the back. Nothing on the dashboard reports a failed stop lamp on most cars, so you have to look.
- Why are both my brake lights not working?
- Both failing at once points at the brake pedal switch rather than the bulbs, since two bulbs rarely die simultaneously. The switch sits up in the pedal box and is a cheap part, though more fiddly to reach than a bulb. Test the switch before buying replacement bulbs you may not need.
- How much does a brake light repair cost?
- A pair of bulbs is usually £3 to £8 and the job takes about fifteen minutes, so doing it yourself is very cheap. A garage will charge roughly £20 to £35. If the fault is the pedal switch, budget £50 to £70 fitted. Sealed LED clusters on newer cars are the expensive exception.
- Why does a brake light matter more than other bulbs?
- Because it is the only warning a following driver gets that you are slowing, and the warning is precisely what is missing. It is the defect most likely to cause a rear-end collision, and in an insurance claim a defective stop lamp makes contributory negligence straightforward to argue against you.
Cars this happens to most
Of every model with at least 2,000 tests in the DVSA data, these record stop lamp not working on the largest share of their MOTs. Across all of them the typical rate is 1.5% of tests.
282 times in 3,438 tests
- Nissan NV2507.8%
176 times in 2,243 tests
1,300 times in 18,893 tests
- Vauxhall Antara6.8%
1,258 times in 18,445 tests
1,229 times in 19,945 tests
- Renault Megane5.6%
5,154 times in 91,287 tests
- Ford B-Max5.6%
2,986 times in 53,638 tests
- Ford Fusion5.5%
2,569 times in 46,353 tests
A high rate here is a property of the fleet as much as the car: these models skew old, and almost everything fails more with age. It is a reason to check the item on a used example, not proof the model is badly built. Models with fewer than 2,000 tests are left out because a rate drawn from a few hundred cars moves too much to rank.
Warning lights behind this
This defect is what a tester writes down. What you see from the driver’s seat is a symbol, and it is worth checking which one, because manufacturers reuse the same shape for more than one system.
This is general guidance, not a diagnosis. The severity DVSA records depends on the specific fault found, so the same item can appear as an advisory on one test and a failure on another. Ask a qualified tester or mechanic to inspect the vehicle.
Has this been recorded on your car?
Check the full MOT history for any UK registration.