Legalities of HID light upgrades


Pro Tuner
Staff member
2002 Clio 172
What are the legalities and implications of converting to HID headlights in a car in the UK?

Are those HID bulb kits practical solutions or should the whole lamp be replaced?
I researched this when I did it on my Signum.

Get a decent kit not a 20 quid ebay special. Get bulbs with metal holders and base. If you do it right HIDS can make a massive difference to the cars looks and to how much you can see at night.

First off I think they only look good on light clusters designed to have them, where a higher model of the same car might come with them as standard. - e.g. projector lenses. On none-projectors they always seem to just dazzle.

The law is hazy and it is down to the individual MOT tester or policeman IMO. The law for HIDs basically states that headlight cleaning and autolevelling systems where fitted must be working. SO if you have OEM HIDS as standard your cleaning/levelling systems must be working.

For aftermarket HIDS some read that as if they aren't there in the first place then they can't be working or none-working so it doesn't matter, others read it as if you fit aftermarket HIDS you should also fit cleaning/levelling systems.

I know people who have had aftermarket for years and sailed through MOTs, others have come a cropper.

I would advise if you are going to fit them try to get a colour and Kelvin rating as near to OEM as you can. Don't have incredibly bright or weirdly coloured ones and you won't draw the wrong kind attention and definitely make sure they are aligned correctly.

One important note too is that they run cool, and if you put them in clusters in place of normal blubs you can get condensation. I used sachets of silicon gel inside the cluster to stop this.

To avoid it altogether site the ballast inside the cluster and make a proper seal where the wiring comes out.

Research your car model, on some cars, as HIDS run low voltage you need a system with a relay to stop the computer reporting a failed bulb.
In my experience projector enclosures respond better to conversion than do complex reflector enclosures with clear lenses. Fluted (fresnel) type headlights don't work at all well. H4 double filament is also an automatic no-no.

I converted my pre-facelit 528i and the beam pattern, alignment and focus were all perfect.

MoT is interesting:

1. A pass does not automatically mean something is technically road legal;

2. The MoT tester will only look for pattern and alignement to be correct;

3. Both (head)lights need to emit the same colour light as each other;

4. The tester is not allowed to dismatle the vehicle as part of the test.

What can we determine from this? Very little.

There are a few UK specific bits of legislation. HiD must be accompanied by headlight washing system. Automatic beam levelling must be fitted, although self-levelling suspension is acceptable.

Beam levelling and suspension levelling are not tested. Washers (if fitted) must work.

Any car which receives EU Type Approval MUST be accepted under UK legistlation regardless of all the above!!

There is still no specific law which forbids the fitment and usage of HID conversion kits. The nearest I have found is a paper which states something along these lines:

'In the [dft] department's opinion it is not legal to sell, fit nor use aftermarket HID lighting kits'.

This is very vague. Opinions form no part of law!!
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It would also still technically be a disclosable modification to your insurers, I bet most who do HID conversions forget to do this.

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