Where is the automatic headlight sensor located?

[CyberPMG]

I've had this issue for most of the 10 years of owning the car. It's a mild annoyance, but I want to try to figure out the problem. I can be driving along and it can be during the day (even in bright sunlight) or night when I will randomly get the alarm from the cluster with the warning image that would normally be for the headlight leveling sensors (Xenon headlights). If this happens during the day, I will also see the headlights turn completely on for a second or two and then turn off (have the switch in Auto mode). When I scan for error codes, it will only report that the automatic headlight sensor had a short. This doesn't happen all the time I'm driving, but now seems to be happening more and more frequently.

I haven't had much luck finding any information about where the automatic headlight sensor is located and what is needed to replace it. I know it's not the little plastic bubble in the dash as that's the receiver antenna for our remote keyfobs. Would the sensor be tied into the same sensor in the rear view mirror that triggers auto dimming? If so, would the easy solution be to replace the rear view mirror? Is there something else I should be checking?

Any info would be appreciated.

'04 B6 A4 Ultrasport - 302,000+ miles and rolling!

[imnuts]

The sensors are by the suspension in the driver's side front and passenger side rear. The module they go into is under the fan behind the glove box.. I believe the sensors are blue.

Edit: And I need to read the full post. I thought the sensor was on the dash by the front speaker.

Sent from my Nexus 6

[CyberPMG]

The sensors are by the suspension in the driver's side front and passenger side rear. The module they go into is under the fan behind the glove box.. I believe the sensors are blue.

Edit: And I need to read the full post. I thought the sensor was on the dash by the front speaker.

Sent from my Nexus 6

Aren't those the sensors used for the auto leveling feature of the Xenon headlights? My issue is around the Auto Headlight sensor. I thought I read the sensor in that plastic bubble by the front speaker in the dash was the antenna to receive signals from the keyfob.

[seanf86]

could it be in the rear view mirror? my S4 dimming mirror has 2 sensors in it and its not a rain sensing mirror.

[MacFady]

Just out of curiousity, have you noticed whether you get the warning if you are carrying something in the back (not sure if Avant or Sedan)? I get the symbol intermittently as well (USP Avant), I don't have it in auto so I've never noticed the headlights flick on or anything, but seems to happen more frequently when I have a suitcase or the like in the rear. That being said I also get it (intermittently) on the exact same 1km stretch of highway when there is nothing in the car but myself. I always chocked it up to the suspension.

[BARRY]

dash near the center grill no? does it go in place of the UV light sensor that MY2002's had?

[PreciseD]

Is it the sensor in the instrument cluster?

I thought the bubble on the dash is a temp sensor used for the AUTO feature on the HVAC unit and the receiver for the remote is combined with our antenna module.

[BARRY]

i believe i've read from i think old guy or diagnosicator mentioned in another posted that the HVAC sensor is in the tiny grill's in the HVAC unit itself. the small rectangular bubble on the dash center grill was a UV light sensor for MY2002's which was replaced by the auto headlight sensor in later years. the UV light sensor controls the auto vent direction which i really really miss as the 2004 model doesn't do this as well as the 2002. I'd almost trade someone my car just to have the better automatic vent direction function.

i could be wrong though...