Are LED headlights legal in the UK, and are Xenon bulbs designed to retrofit without a conversion kit?
Most conversions are illegal in the UK. The reason is that UK Construction and Use laws were written before the technology existed. Factory-fit xenon HID and LED lamps are legal not because they meet UK regulations (they don’t), but because the car has been approved under European Whole Vehicle Type Approval with the lamps fitted, and the UK recognises this approval. Therefore, unless the conversion uses all (and only) the factory parts (including the automatic levelling using sensors on the suspension), it does not meet the Type Approval, so is not legal in the UK. Normal incandescent (filament) bulbs using xenon rather than argon as the filler gas are not affected, so are legal.
