Dazzle can also be caused if the lamps are dirty or aimed too high due to, for example, carrying
rear seat passengers and/or heavy items in the boot. Vehicles with HID headlamps are therefore
required to have a headlamp washing system (a wiper is not required) and be self levelling, which
may be achieved either by the use of either headlamp or suspension levelling systems.

The presence and operation of these headlamp cleaning and levelling devices has been
added to the test. Therefore, if a mandatory headlamp levelling or cleaning device is missing,
inoperative or otherwise obviously defective, the vehicle will fail.

This raises the question of whether these checks apply to vehicles fitted with after-market HID
lighting kits. These kits convert conventional halogen headlamps to HID Xenon and they are
widely sold and fitted to vehicles used on the road. The Department for Transport considers
that after-market systems should be required to meet the same safety standards as that applied
in respect of these lamps at vehicle Type Approval. Therefore, in order to pass the MOT
test, vehicles fitted with after-market HID systems would also need to be fitted with headlamp
cleaning and self-levelling systems. Some high specification estate cars are fitted with a selflevelling suspension system and this would be considered as adequate for the purpose.

It is also worthy of note that a few high performance vehicles fitted with HID headlamps that
have barely any luggage space and stiff suspension do not require a self-levelling system