Are LED headlight bulbs legal in the UK?

That covers most cars. Of the 360 UK car generations we've verified, 295 use a halogen bulb (H7, H4 or H11) for dipped beam, and 43 have factory LED dipped beams.

Do LED headlight bulbs fail the MOT?

Yes, when they're fitted into a halogen headlamp. Section 4.1.4 of the MOT inspection manual, which covers headlamps, lists a halogen unit fitted with HID or LED bulbs as a reason for failure on vehicles first used from 1 April 1986.

Factory-fitted LED and xenon headlamps are fine. They were designed and approved as complete units with that light source, so the issue only arises when the light source is changed after the car left the factory. The manual is the authority on what a tester checks, so it's worth reading the headlamp section yourself if you're unsure about your car.

Why aren't LED bulbs allowed in halogen headlights?

A halogen headlamp's reflector or projector is shaped around the exact position of a glowing filament. The bulb's base locks that filament into a precise spot, which is why bulb types such as H7 and H4 have their own bases.

An LED "bulb" puts its light-emitting chips in a different place and throws light in a different pattern. Even if it fits the socket, the headlamp can't control that light the way it was designed to. The result can be a scattered beam with light spilling above the cut-off, which dazzles oncoming drivers, or dark patches where you need light on the road.

Headlamp aim and operation are checked on every UK MOT. Driving with defective lights can also lead to a fixed penalty.

How do I know if my car has factory LED headlights?

Check the handbook, your car's generation page and the headlamp itself. Factory LED headlamps usually have no bulb to change at all; our car pages show these as "LED (non-replaceable)".

Some examples from our verified data:

The Kuga Mk3 is a good example of a mixed car. It has plenty of factory LEDs, but the dipped beam is still an H7 halogen bulb, so an LED H7 in that position would be a conversion.

Lamp type can also change within a generation by trim or facelift. If you're unsure, our guide on how to tell halogen, xenon and LED headlights apart walks through the visual clues.

What if my factory LED headlight stops working?

Factory LED headlamps are usually replaced as a module or a whole unit rather than a bulb. That's normally a job for a dealer or specialist. Our guide to non-replaceable LED lights explains what to expect and why buying an "LED bulb" won't help.

Do I need to tell my insurer about LED bulbs?

Insurers generally ask you to declare modifications to your car, and a lighting conversion can count. Policies differ, so check your policy wording or ask your insurer directly before fitting anything that changes the car from how it left the factory. An undeclared modification can cause problems if you make a claim.

What can I fit instead of LED bulbs?

If you want more light from halogen headlamps, the legal option is a higher-performance halogen bulb with the same code as the original: an H7 for an H7, an H4 for an H4. These are built to the same dimensions and filament position, so the headlamp works as designed.

A few practical points:

• Replace in pairs. Matched bulbs give the same output and colour on both sides. See should you replace headlight bulbs in pairs.
• Check the stated life. Some higher-output halogen bulbs have a shorter rated life than standard ones; the packaging usually says.
• Keep the lenses clean and the aim right. A dirty or misaimed headlamp loses more useful light than any bulb upgrade adds.
• Get the code right first. Our H7 vs H4 vs H1 guide explains why the codes can't be swapped.

What about LED sidelights and number plate bulbs?

This is less clear-cut than headlamps. LED replacements for small bulbs such as W5W are widely sold, but they can trigger bulb-failure warnings on cars that monitor the circuit, and the light must still be the correct colour: white at the front for sidelights and white for the number plate.

Every MOT checks sidelights and number plate lamps. Rather than rely on a product listing, read the relevant sections of the MOT inspection manual for your car's age. Our W5W vs C5W guide covers these bulbs in detail.

Check your car

See which positions on your car use halogen bulbs and which are factory LED:

• Ford Kuga Mk3 bulbs
• Renault Clio V bulbs
• Ford Fiesta Mk8 bulbs
• VW Golf Mk7 bulbs
• Vauxhall Corsa F bulbs

Or browse every car on the bulbs page.

Common questions

Are LED headlight bulbs illegal in the UK?

Fitting LED bulbs into a headlamp designed for halogen is an MOT fail on cars first used from 1 April 1986, under section 4.1.4 of the MOT inspection manual. LED headlamps fitted at the factory are legal.

Will an LED H7 bulb pass the MOT?

Not in a headlamp built for a halogen H7. The manual treats that as a halogen unit converted to LED, which is a fail. A halogen H7, including a higher-performance one, is the correct replacement.

Can I get stopped for LED headlights?

Driving with defective lights can lead to a fixed penalty, and lights that dazzle other road users are a safety problem whatever the bulb. Keeping to the bulb type your headlamp was designed for avoids the issue.

Are xenon (HID) conversion kits legal?

The same rule applies. A halogen headlamp unit converted to HID is an MOT fail on vehicles first used from 1 April 1986. Factory-fitted xenon headlamps are fine.

Checked against our verification rules. Spotted something wrong? Tell us.