How Can Headlamps Fail My MOT?

Your headlamps are one of the most vital safety features on your vehicle, especially during night-time or poor weather driving.

If something’s not quite right with them, it could be flagged during your next MOT.

But what exactly can go wrong? And more importantly, which issues are serious enough to result in a failure?

This article will break down how your headlamps are checked during an MOT, the types of faults that could lead to a fail, and what you can do to avoid them.
 

Why Are Headlamps So Important?

Headlamps do more than help you see in the dark – they also make you visible to other drivers and pedestrians.

Whether you’re driving down a country road at night or navigating a rainstorm on the motorway, properly working headlamps are essential.

That’s why the DVSA includes a comprehensive headlamp check in the MOT test.

Faulty headlamps don’t just reduce your visibility – they can also dazzle or endanger other road users, making them a serious safety concern.
 

How Are Headlamps Checked During an MOT?

During the MOT test, the examiner will inspect your headlamps for:

• Condition and security – Are they securely fitted and free from serious damage?
• Operation – Do they switch on and off correctly? Do dipped and main beam modes work as expected?
• Alignment – Are they angled correctly, or are they shining too high or too low?
• Light output and colour – Is the beam clear and the colour compliant with UK road laws?
• Switch functionality – Do the ‘on’ and ‘dip’ switches operate in line with regulations?

In newer vehicles, additional systems such as manual levelling devices and headlamp cleaning systems are also subject to checks – especially if your vehicle is equipped with LED lights.

Will Faulty Headlamps Cause an MOT Fail?

Yes, in many cases, headlamp faults can lead to a major defect, which results in an automatic MOT failure.
The following are some of the most common reasons headlamps can fail the MOT:
 

1. Headlamp Not Working Properly

This is one of the most frequent causes of MOT failure.

If one or both of your headlamps are, completely inoperative or missing, it will result in a major defect, therefore failing your MOT test.

Even if only half of the LEDs are out, it may be classed as a minor defect – but this could still lead to issues further down the line.

If your headlamp seems dim or flickering, it could be a sign that the bulb is nearing the end of its lifespan. Get it replaced early to avoid a potential fail.
 

2. Poor Headlamp Alignment

Headlamp alignment is checked using specialist equipment to ensure the beam is angled correctly.
If your headlamps are aimed too low, they won’t adequately light the road ahead. Too high, and they could dazzle oncoming drivers.
This fault is classified as a major defect if:

• The aim is outside the legal limits
• The alignment cannot be tested
• The beam pattern is obviously incorrect

This issue is especially common after suspension work or minor front-end collisions – so if your car’s had any recent repairs, it's worth getting the alignment checked.
 

3. Cloudy or Yellowed Headlamp Lenses

Over time, UV rays and road debris can cause your headlamp lenses to become cloudy or discoloured.

While this might seem cosmetic, it can actually reduce light output.

If it significantly affects visibility, it can lead to a major defect during the test.
 

4. Incorrect Light Colour or Intensity

All mandatory headlamps must emit either a white, yellow light, or predominantly white with a slight blue tinge (some HID systems display this light colouring).

If the light emitted is any other colour – or the beam intensity is compromised due to a damaged bulb or lens coating – this will likely result in a major MOT failure.

In four-lamp systems, the inner and outer pairs don’t need to match exactly, but they must each still emit an approved colour.
 

5. Dip and Beam Switching Not Working

The MOT tester will check that your dipped beam and main beam:

• Activate instantly when switched on
• Switch back and forth properly when using the dip switch
• Follow legal switching patterns (e.g. dipping both main beams or extinguishing them while dipped beams remain active)

If your headlamps don’t switch correctly between modes, it will be marked as a major defect.
 

6. Levelling and Cleaning System Faults (HID/LED)

For vehicles fitted with HID (High-Intensity Discharge) or LED headlamps – especially those first registered after September 2009 – MOT testers will also check the:

• Manual or automatic headlamp levelling system
• Headlamp cleaning device (e.g. washer jets)

If these systems are not working properly, they may lead to a major defect. This is especially relevant for modern vehicles where levelling is electronically controlled.

Final Thoughts

Your headlamps are more than just a convenience – they’re a critical safety feature and a key component of your MOT test.

Whether it’s a faulty bulb, poor alignment, or a clouded lens, any defect that affects their performance can result in a fail.

The good news? Most headlamp issues are quick and affordable to fix – especially if you spot them before test day.
Here’s how to stay on top of things:

• Regular car servicing
• Check all lights work properly, especially before your MOT
• Replace flickering or dim bulbs as soon as you notice them
• Clean foggy or yellowed lenses to restore light clarity
• Avoid DIY bulb conversions unless using a full compliant headlamp unit

By keeping your headlamps in proper working order, you’ll not only boost your chances of a pass – you’ll also make the roads safer for everyone.
 

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