MOT defect file
Horn not working, or of the wrong type
Last updated
Quick answer
The horn did not sound, was too quiet to be useful, or is a type the rules do not allow. Anything that alternates between notes — an air horn, a musical horn, a two-tone — fails even when it works perfectly.
- Typical cost
- £20–£120
- DIY viability
- Straightforward
What you might notice
- Nothing at all when you press the pad, or a click from behind the grille with no note
- A weak, wheezy or intermittent sound, often worse in wet weather
- A horn that works only when the wheel is at a particular angle, which points at the clockspring rather than the horn
- An aftermarket air horn or musical horn that works perfectly and still fails, because the type itself is not permitted
What causes it
- Corrosion inside the horn unit itself, which sits low behind the bumper or grille and takes the full spray off the road
- A blown fuse, a failed relay, or a corroded earth at the horn bracket
- A worn clockspring or a dirty contact in the steering wheel, which is also the circuit the driver's airbag uses
- A previous owner's aftermarket horn: multi-tone, siren or novelty types are not acceptable regardless of how well they work
Advisory or failure?
An audible warning that is not working is a major defect, and one not in accordance with the requirements is also a major defect. Only the control being insecure is treated more leniently, at minor. The requirements themselves are the part people trip over. The warning must be loud enough to be heard by other road users, and on vehicles first used on or after 1 August 1973 the sound must be continuous or uniform and must not be harsh or grating. Gongs, bells, sirens and anything with more than one tone are not permitted as an audible warning, so a two-tone or musical horn fails on type even in perfect working order — a two-or-more-tone horn being one that automatically alternates between fixed notes at regular intervals. Vehicles first used before 1906 are the only exception, where a gong, bell or siren is acceptable. Note also that a reversing alarm or an alarm system's siren is a separate matter and does not satisfy the requirement for a horn.
Can you fix it yourself?
Straightforward
Work outwards from the cheap end. Check the fuse, then have somebody press the pad while you listen at the horn: a click means power is arriving and the unit has failed, silence means the fault is upstream in the relay, the switch or the earth. The horn itself is usually one bolt and one or two wires, behind the front bumper or up beside the radiator, and a replacement is a few pounds — clean the bracket and the earth point while you are there, because corrosion at the mounting is a frequent cause of a weak note. Two cautions. If the fault is in the steering wheel, stop: that circuit shares the airbag clockspring, and the wheel and its airbag should not be disturbed casually. And if you are fitting a replacement, fit a single-tone unit that is E-marked for road use rather than the twin-tone set sold as an upgrade, or you will have swapped one failure for another.
What it costs
A replacement single-tone horn is £10 to £30 and takes twenty minutes, so a garage will usually charge £30 to £60 including the part. A relay is £8 to £20, and an earth or wiring repair is charged as labour — half an hour to an hour, which is where the middle of the band sits. The top of the band is a fault in the steering wheel circuit: a clockspring is £60 to £200 fitted depending on the car, and because the airbag has to come off the wheel to reach it, this is not the job to shop on price for.
What happens if you ignore it
The horn is the only way you can warn somebody who has not seen you, and the moments it exists for — a car drifting out of a side road, a pedestrian stepping off a kerb — do not allow for a second attempt. It is also the cheapest possible item to fail on, so paying for a retest over a £15 part and twenty minutes is a poor outcome. Where the cause is the steering wheel circuit rather than the horn, leaving it means leaving a fault in the same wiring that fires the driver's airbag, and that is likely to bring the airbag warning lamp on and a second major defect with it.
Common questions
- Is a horn that does not work an MOT failure?
- Yes. An audible warning that is not working is a major defect, and one that does not meet the requirements is also a major defect. Only an insecure horn control is treated more leniently, at minor. The sound has to be loud enough for other road users to hear, and on vehicles first used from 1 August 1973 it must be continuous or uniform and not harsh or grating.
- Will an air horn or a musical horn fail an MOT?
- Yes, on type alone, even in perfect working order. Gongs, bells, sirens and anything with more than one tone are not permitted, a two-or-more-tone horn being one that automatically alternates between fixed notes at regular intervals. Only vehicles first used before 1906 may use a gong, bell or siren. A reversing alarm or an alarm system's siren does not satisfy the requirement either.
- Why does my horn only work at certain steering wheel positions?
- That points at the clockspring or a dirty contact in the steering wheel rather than the horn itself. Worth knowing: the same circuit carries the driver's airbag, so leaving it can bring the airbag warning lamp on and a second major defect with it. The wheel and its airbag should not be disturbed casually, so this one belongs with a garage.
- Can I replace a car horn myself?
- Usually yes. Check the fuse first, then have somebody press the pad while you listen at the horn: a click means power is arriving and the unit has failed, silence means the relay, switch or earth. The horn is normally one bolt and a couple of wires behind the bumper or grille. Fit a single-tone E-marked unit, not the twin-tone set sold as an upgrade.
- How much does it cost to fix a horn?
- A replacement single-tone horn is £10 to £30 and takes twenty minutes, so a garage will usually charge £30 to £60 including the part. A relay is £8 to £20, and an earth or wiring repair is half an hour to an hour of labour. A clockspring in the steering wheel is the top of the band at £60 to £200 fitted.
Cars this happens to most
Of every model with at least 2,000 tests in the DVSA data, these record horn not working, or of the wrong type on the largest share of their MOTs. Across all of them the typical rate is 0.6% of tests.
- Volkswagen LT2.8%
69 times in 2,480 tests
- MG TF2.4%
209 times in 8,683 tests
- Peugeot Partner2.4%
3,585 times in 150,542 tests
- Suzuki Baleno2.4%
158 times in 6,685 tests
- Citroen Berlingo2.3%
4,176 times in 179,716 tests
- Peugeot 2052.2%
73 times in 3,268 tests
- Citroen Saxo2.1%
60 times in 2,906 tests
- Talbot Express2.1%
99 times in 4,826 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.
The warning light 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.
Fault codes behind this failure
A failure certificate records that the lamp was lit, not what lit it. If this is what your certificate says, one of these codes is usually stored behind it, and reading it is the difference between a diagnosis and a guess.
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.