Products on the lens or light source that obviously reduce the light's intensity or change its colour will become a reason for failure – applies to front/rear position lamps, registration plate lamps, stop lamps, rear fog and direction indicators,
Headlight requirements are updated to take account of the particular characteristics of High Intensity Discharge (HID) lamps.
HID headlights can cause dazzle if they are dirty or aimed too high so car manufacturers must fit headlamp cleaning and levelling systems. Where HID or LED dipped beam headlamps are fitted the tester will switch on the headlamps and check the operation of any headlamp levelling and cleaning devices fitted.
The car will fail if a headlamp levelling or cleaning device is inoperative or otherwise obviously defective.
If a headlamp bulb is not seated correctly the resulting beam pattern will be indistinct and this will result in a test fail.