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LED Lights & Your MOT

We often have vehicles turn up with aftermarket exterior LED lighting, normally its just the headlights, but it can be all of the exterior lights. Although they seem to be working perfectly, folk will often be surprised when the MOT test, results in a fail, due to the exterior lighting.

In 2021 the rules were made clear regarding the changing of exterior lighting and the MOT.

LED headlights: Are they allowed in the UK?


There are strict rules dictating each feature of your vehicle and headlights are no exception. In recent years, Light Emitting Diodes, or LEDs, have become the preference for many drivers over traditional halogen bulbs. But there’s a big catch: they aren’t always road legal in the UK. If you're thinking of buying an LED headlight conversion kit, don't do anything until you've read this article.


Are LED headlights legal in the UK?


Most cars, bought today, will have the option of LED headlights. When fitted by the manufacturer, they’re perfectly legal, and while they may appear brighter than halogen bulbs are within legal limits for dazzle.


However, there is another type of LED headlights which are illegal for road use in the UK: aftermarket LEDs. These are LED bulbs that are put in after a car has left the factory and are not part of the original equipment provided by the original manufacturer.


Can I replace my halogen headlights with LED bulbs?

You are not allowed to retrofit LED bulbs onto your car, because there is different technology within the headlight unit itself that is required to make an LED headlight safe and effective.


Halogen bulbs use a specific type of reflector to shine the light they produce in the right direction. Stick an LED bulb in the unit instead, and you’ll find that it’s much brighter, less focused, and far more likely to dazzle other road users. The light might even end up scattered and may not illuminate the road properly crucial for driving at night, particularly on unlit countryside roads.


LED headlights require different lenses to halogen bulbs basically a whole different technological system and need to be correctly aligned to make them safe on the roads. And at the moment there’s no way of regulating aftermarket LEDs.


There are also reports of retrofitted LED bulbs causing electrical problems in cars that aren’t designed for them.


Why can I still find LED bulbs for halogen headlights being sold online?

Type: ‘LED headlight conversion kit’ or ‘LED headlight bulbs’ into any search engine, and you can find plenty of options: even reputable dealers sell them. It all sounds very promising, but don’t be fooled.


While some vendors are unscrupulous, others get away with selling LED headlight bulbs because they’re only illegal on the roads or in public places (like private car parks). There are different rules for driving on private land that doesn’t have public access, including the type of lighting your vehicle requires. So, some LED bulbs or ‘conversion kits’ may have a small disclaimer somewhere, stating ‘For off-road use only’.


What are the advantages of LED headlights?

A lot of people want LED headlights. And taillights, brake lights, fog lights. But why?

LED bulbs tend to be much longer lasting than traditional halogen bulbs, so you’re less likely to find that one of your car lights has failed. They also use a fraction of the energy that traditional halogen bulbs do. They don’t heat up in the same way, so are much more efficient at producing light, meaning that they don’t require your energy supply to work quite so hard. And let’s not forget that they can look cool, too.


✓ Cost efficient

✓ Durable

✓ Energy efficient

✓ Stylish


Are there any disadvantages to LED headlights?

As they tend to be part of one closed unit, if one of your headlights were to break or fail, it would have to be completely replaced a far more expensive procedure than simply changing a bulb. And at the moment, LED lights are often an optional upgrade on newer vehicles, which is going to see you fork out more money.


❌ Expensive initial outlay

❌ Expensive to replace


Don’t my Daylight Running Lights use LEDs?

If you own a model of car manufactured after 2011, it will have to have Daylight Running Lights (DRLs). These are lights that come on automatically with your engine so that you can be seen more easily by other drivers, pedestrians, and cyclists. The bulbs are low wattage and bright (they must be seen in the daylight) and, crucially, yes, some use LEDs. You can even retrofit DRLs onto any vehicle that doesn’t have them. So how does that square with the ‘no aftermarket LED headlights’ rule?


Well, they’re designed for totally different uses. DLRs turn off as soon as you activate your headlights. They’re too bright to use during hours of darkness and, just like retrofitted LED headlamps, can dazzle other road users if they remain on when visibility is limited.



Will LED headlights pass an MOT?

LED headlights fitted by the manufacturer should pass an MOT just fine, so long as they are working correctly. This means that they:

✓ Match (i.e. they should be the same size and emit the same colour light)

✓ Function well

✓ Are positioned correctly

✓ Have a working lens

✓ Are securely attached

✓ Are properly aligned

✓ Switch between dipped and full beam instantly

✓ Move in accordance with headlight levelling controls

✓ Have functioning headlamp washers (if applicable)


However, retrofitted LED headlights are not road legal in the UK, and will fail an MOT. This has been the case since 2021, when the MOT inspection manual was updated (previously it was a grey area). It reads:


“Existing halogen headlamp units on vehicles first used on or after 1 April 1986 must not be converted to be used with high intensity discharge (HID) or light emitting diode (LED) bulbs. If such a conversion has been done, you must fail the headlamp for light source and lamp not compatible.”


So, unless you have a classic car that predates April 1986, you’ll be told to switch back to halogen bulbs before your vehicle’s deemed roadworthy.


Can you fit LED bulbs in taillights?

The law prohibits retrofitting LED bulbs on any external lights on your vehicle, so unless they’ve been fitted as Original Equipment (how your car comes straight from the factory), you won’t be able to use them in your taillights, brake lights or fog lights.

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