Eventually, any motorist in the UK will have to put their vehicle through for an
MOT inspection, regardless of the vehicle class.
Every vehicle on the road must have a functioning horn fitted as a legal requirement.
Because it plays such an important role in road safety, the horn is thoroughly checked during an MOT test.
This article will explain how a car horn can fail your MOT through the lens of the DVSA MOT guideline and how to avoid
MOT failure in this category.
What Is a Car Horn and Why Is It Important?
A car horn is a simple but essential safety device designed to warn other motorists, cyclists, and pedestrians of your presence.
It provides an audible signal in situations where a visual warning may not be enough, such as when another vehicle is about to pull out or when a pedestrian steps into the road.
For modern vehicles, the horn is usually activated via the steering wheel and must emit a clear, continuous sound that can be easily heard by pedestrians, cyclists, and other drivers.
Can My Car Horn Fail the MOT Test?
Yes, if your horn is faulty, insecure, or not compliant with DVSA requirements, your vehicle can fail its MOT.
During the test, MOT examiners will check that your horn:
- Works when pressed
- Emits a single, continuous, uniform sound
- Is loud enough to be heard by other road users
- Has a secure control or button
If the horn does not meet these standards, the examiner will mark the defect according to its severity.
Reasons a Car Horn Might Fail an MOT
According to
DVSA MOT guidance, there are several clear reasons why a car horn can fail the test:
- Horn not working (Major defect) – If the horn does not sound when activated, the vehicle will fail immediately. This is one of the most common causes of horn-related MOT failures.
- Horn control insecure (Minor defect) – If the horn button or steering wheel control is loose or wobbly but the horn still works, it may be recorded as a minor defect.
- Horn not in accordance with requirements (Major defect) – A horn that does not meet the legal requirements will fail.
The horn must always provide a clear, uniform sound designed for safety.
Anything excessively loud, musical, or distracting is considered unsuitable for road use.
How to Avoid Car Horn MOT Failure
Keeping your car horn in good working order doesn’t require much effort, but a few simple checks can help you avoid an unexpected MOT failure:
- Occasionally test your horn – Press the horn to ensure it sounds the same every time. If the sound is weak, intermittent, or silent, it may indicate a wiring or fuse issue.
- Check the control – Make sure the horn button or steering wheel pad feels secure and responsive. If it feels loose, get it inspected.
- Inspect after maintenance – Sometimes electrical work or steering wheel repairs can affect the horn connection. If you’ve recently had work done, test the horn before your MOT.
By making these quick checks part of your routine, you can minimise the risk of an MOT failure.
My Horn Has Failed the MOT: What Now?
If your horn fails the MOT, the good news is that repairs are normally quick.
To fix your car horn, it may cost anywhere in the range of £40-£120, but could cost more depending on the extent of the fix/independent garage pricing.
In many cases, the fix includes:
- Replacing a blown fuse
- Repairing loose wiring
- Replacing the horn unit itself
Most garages can complete the repair the same day, allowing your vehicle to be retested quickly.
While a failed horn might seem like a small issue, it is vital for your safety and the safety of others on the road.
By maintaining your horn properly and testing it regularly, you’ll not only improve your chances of passing your MOT first time but also ensure you remain a safe, responsible driver.
FAQs:
Will my car fail its MOT if the horn doesn't work?
Yes, a faulty or non-functioning horn is an MOT failure point. The horn is classified as a safety-critical component, and testers are required to check that it works correctly and produces a continuous, uniform sound that is loud enough to be heard by other road users.
What horn faults will cause an MOT failure?
Common horn-related MOT failures include the horn not sounding at all, producing an intermittent or weak sound, making an unusual noise such as a rattle or buzz, or being insecure and poorly mounted. A horn that sounds continuously without the button being pressed will also result in a failure.
Does the type of horn sound matter for the MOT?
Yes, UK law requires that a vehicle horn produces a single, continuous, and uniform tone. Musical horns, multi-tone sirens, or horns that mimic emergency service sounds are not permitted on standard road vehicles and will result in an MOT failure if fitted.
Can I fix my horn before the MOT to avoid a failure?
Absolutely. If you suspect your horn is not working correctly, it is worth having it inspected and repaired before your MOT test. Common fixes include replacing a blown fuse, fitting a new horn unit, or repairing a faulty steering column switch — all of which are relatively straightforward and inexpensive repairs.
Is a horn failure classed as a major or minor MOT defect?
A non-functioning or non-compliant horn is classified as a major defect under the MOT testing scheme, meaning the vehicle will receive an outright failure and cannot be driven until the fault is rectified and the car re-tested or re-inspected.
How do I know if my horn will pass the MOT?
You can do a quick check yourself before your test. Press the horn button firmly and listen for a loud, clear, and consistent tone. If there is no sound, the sound is faint, cuts in and out, or sounds distorted, it is likely to fail. Having the vehicle inspected by a mechanic beforehand will give you peace of mind.
