headlight issue on s4 - Any ideas

[Tella27]

My driver's side headlight dips out and then comes back on over and over - dash lets me know about it. When my fog lights are on the headlight stays on but dash still says its out. Turn fogs off and it'll dip in and out. Anyone have this problem? Thought it was a bulb at first but since it stays on with the fogs I don't believe that to be the case anymore - ballast maybe but how would the fog lights have anything to do with the ballast - also why would the dash still tell me it's out? Any help with this would be greatly appreciated

[bbtri]

This is just a guess, but maybe a problem with the switch? The switch is in a different position with the fogs on.

[bmwpower603]

Could still be the bulb/bulbs.
I had a similar problem. Replaced the faulty bulb, and had the same issue. Then I tried replacing both bulbs. And that indeed fixed the problem.

The bulbs work in conjunction with each other.

[Tella27]

I bought 2 new bulbs so hopefully it fixes the issue - it's weird that there are no problems with the fogs on but it still sends the signal of it being out. Thanks

[bmwpower603]

Put those in. If they don't work just return them.

Could be a ballast problem also.. But id start with the bulbs

[JimmyBones]

Put those in. If they don't work just return them.

Could be a ballast problem also.. But id start with the bulbs

Usually there is no return on electrical parts, especially if they are plugged in.

OP, This problem is either the Xenon headlight bulb or the ballast. If you can DIY then swap the bulbs from side to side. If the problem follows the bulb then you need a new bulb. If the problem doesn't swap with the bulb then you need a ballast most likely. The bulbs are cheaper than the ballasts. You probably have a B7 S4 right?

It is common for the headlight to go out and then come back on if you cycle the switch with this problem. I have seen that a lot and it happened with my old A6 for a while too until the ballast totally failed.

[drinkbrew]

I have the same problem, I found this write up that may help.

http://nickscarblog.com/diy/how-to-f...ror-on-an-audi