Removethe plastic cover that runs across the front of the car at the top of the grill. There's a long torx screwdriver in the toolkit in the boot there are four torx screws on the headlight, two need loosening and two need removing iirc. Then the whole headlight slides out. Take the cap off and the headlight bulb just twists and releases.
TheAudi A4 B8 or internally known to Audi as the Typ 8K was unveiled in 2007 with the vehicles going on sale in 2008. The B8 was built on a different platform which allowed for a different wheelbase length without an increase in total length of the vehicle. This resulted in a much better handling car and bigger leg room and and boot size. The Anyway This bulb is a bitch to replace. 1. It is on a weird angle, and 2. the wire-harness going to the bulb is really short. It took some fiddling but here is what i did to get it out. 1. The bulb is behind the smaller cover on the inner side of the headlight housing (meaning closer to the front grille). 2. 8ajj9.audi a4 b8 bulb list
