Is a headlight not working an MOT failure?

Yes. There is no advisory grading for a mandatory lamp that does not light: it is a major defect and an automatic failure, and that applies to one dipped beam as much as to both. A lens clouded or damaged badly enough to materially reduce light output fails in its own right, as does a headlamp levelling device that no longer works.

Can I drive with one headlight out?

You should not. Driving with a headlamp out is an offence and attracts a fixed penalty. It also halves what you can see on an unlit road and makes the car harder for other drivers to place, because a single lit lamp reads like a motorcycle at a distance.

How much does it cost to replace a headlight bulb?

A halogen bulb is £8 to £20 with nominal labour where access is good, so plenty of these jobs are settled for under £30. Poor access adds about an hour of labour. A xenon bulb at £40 to £90, or a ballast at £100 or more, sits at the top of the band, and a complete LED assembly costs considerably more again.

Should I replace both headlight bulbs at once?

It is worth doing. Both bulbs have done the same hours, so the second is rarely far behind the first, and a fresh bulb alongside an old one gives noticeably uneven light. Handle the glass with a cloth rather than bare fingers, because skin oil creates a hot spot that shortens bulb life.

Does a partly failed LED headlight fail the MOT?

The grading splits for headlamps that use multiple light sources, as LED units do. If at least half the sources still work it is a minor defect and the car passes with it recorded; fewer than half working is a major defect and a failure. Sealed LED units are generally not serviceable, so the fix is a whole assembly.

MOT defect file

Headlamp not working

Last updated 8 September 2026

Quick answer

A headlamp did not illuminate on test. Usually a bulb, but can be wiring, a connector or a failed control module.

Typical cost: £20–£120
DIY viability: Possible with care

The MOT checks operation, colour, security and condition. Lamps designed as pairs should both work and should match in colour and broadly in intensity. Applicable high-level brake, rear fog, reversing and number-plate lamps are also checked.

What you might notice

One side of the road ahead noticeably darker than the other after dark
Dipped beam working while main beam does not, or the reverse, on a car with a twin-filament bulb
Flickering, or a lamp that cuts out over bumps and comes back on a smooth surface
A bulb warning on the dashboard — though plenty of cars monitor exterior lamps loosely, and some not at all

What causes it

A blown filament, which is simply the end of a halogen bulb's life at around two to five years
A corroded holder or connector, common once the rear seal on the headlamp has perished and let water in
A failed HID ballast or igniter on a xenon system, or a failed driver module on an LED unit
Chafed wiring between the headlamp and the fusebox, or a blown fuse that is really pointing at a short elsewhere

Advisory or failure?

There is no advisory grading for a headlamp that does not light: a mandatory lamp failing to operate is a major defect and an automatic failure, and that applies to one dipped beam as much as to both. Where the headlamp uses multiple light sources, as LED units do, the grading splits — at least half still working is a minor defect, fewer than half working is a major. A lens discoloured, clouded or damaged badly enough to materially reduce light output is a major defect in its own right, and a headlamp levelling device that no longer functions is treated the same way.

Can you fix it yourself?

Possible with care

On an older car with a halogen bulb this is a ten-minute job and a £10 part, and it is worth changing both sides together because the second bulb will not be far behind. Handle the glass with a cloth, since skin oil creates a hot spot that shortens bulb life. Access is the real variable: on many modern cars the only route to the bulb is through a wheel arch liner, or with the battery or front bumper removed, which turns a trivial job into an hour. Xenon systems carry a high-voltage igniter and are best left alone, and sealed LED headlamps are generally not serviceable at all.

What it costs

A halogen bulb is £8 to £20 with nominal labour where access is good, so many of these are settled for under £30. Poor access adds an hour of labour, and a xenon bulb at £40 to £90, or a ballast at £100 or more, sits at the top of the band. Complete LED headlamp assemblies fall outside it altogether, since the unit is replaced whole rather than repaired.

What happens if you ignore it

Driving with a headlamp out is an offence and attracts a fixed penalty, and it halves what you can see on an unlit road while making the car harder for others to place — a single lit lamp reads like a motorcycle at a distance. Water that got in far enough to corrode one holder is still in there, working on the reflector coating and the rest of the connector, so the cost only goes one way.

Common questions

Is a headlight not working an MOT failure?: Yes. There is no advisory grading for a mandatory lamp that does not light: it is a major defect and an automatic failure, and that applies to one dipped beam as much as to both. A lens clouded or damaged badly enough to materially reduce light output fails in its own right, as does a headlamp levelling device that no longer works.
Can I drive with one headlight out?: You should not. Driving with a headlamp out is an offence and attracts a fixed penalty. It also halves what you can see on an unlit road and makes the car harder for other drivers to place, because a single lit lamp reads like a motorcycle at a distance.
How much does it cost to replace a headlight bulb?: A halogen bulb is £8 to £20 with nominal labour where access is good, so plenty of these jobs are settled for under £30. Poor access adds about an hour of labour. A xenon bulb at £40 to £90, or a ballast at £100 or more, sits at the top of the band, and a complete LED assembly costs considerably more again.
Should I replace both headlight bulbs at once?: It is worth doing. Both bulbs have done the same hours, so the second is rarely far behind the first, and a fresh bulb alongside an old one gives noticeably uneven light. Handle the glass with a cloth rather than bare fingers, because skin oil creates a hot spot that shortens bulb life.
Does a partly failed LED headlight fail the MOT?: The grading splits for headlamps that use multiple light sources, as LED units do. If at least half the sources still work it is a minor defect and the car passes with it recorded; fewer than half working is a major defect and a failure. Sealed LED units are generally not serviceable, so the fix is a whole assembly.

Cars this happens to most

Of every model with at least 2,000 tests in the DVSA data, these record headlamp not working on the largest share of their MOTs. Across all of them the typical rate is 1.1% of tests.

Talbot Express9.5%
460 times in 4,826 tests
Volkswagen LT9.0%
222 times in 2,480 tests
Chevrolet Captiva5.8%
277 times in 4,737 tests
Jeep Cherokee4.9%
437 times in 8,958 tests
Nissan Pathfinder4.8%
228 times in 4,726 tests
Smart (mcc) City4.8%
201 times in 4,194 tests
Hyundai I8004.3%
340 times in 7,916 tests
Vauxhall Antara4.3%
792 times in 18,445 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.

Pass rates for every make and model

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.