internecine

is it the bulb? most likely the ballast, right?

this happened after they were on for about 2 hours. parked overnight, then it was gone the next morning.

iconoclast

jk, most likely the ballast.

WindyCityS4

This was a sign of the bulbs going on a friends S4.

Green Maryland S4

Most likely the ballast. If you want to be sure, swap the ballasts on your headlights and see if the problem follows the ballast, or the headlight assembly. You will need a Torx 20 bit to get the headlamps out, and a Torx "security" (ie. with a hole drilled in the middle) bit to get the ballasts out.

Theoreticaly, it could also be the headlamp starter or a flaky electrical connection, but the ballast would be the highest probability. I recently had to replace my ballast, and I had to beg the Stealership for a discount. The original list price was over $600, but I haggled them down to a mere $510. Such a deal. I have an early build car, so I couldn't find one that I was sure would work on E-bay.

nadrealista

btw if it is ballast..just buy whole headlight form junkyard(car-parts.com)..I got mine for 250...just swapped the whole headlight..

auditurbo84

I ended up just going with an aftermarket setup. I have a ballast if you end up needing one.

internecine

its actually a stage 3 kit from SPP