Putting this in for the archive. I have a 2001 Audi TT Roadster, 101,000 miles. Airbag light came on shortly after purchased (bought used in 2010 with 94,000) intermittently. Would sometimes come on at start, then cut off after car had run for a few minutes, mostly on longer road trips 20 or more miles.
Then about 2 months into ownership the alternator/battery light came on, replaced alternator with new. Mechanic (who I trust) said the voltage regulator was fried and had been for some time, probably from the car lot jumping it off after a dead battery.
Like magic after about 15 starts with the new alternator, airbag light went off and stayed off for about 8 months. No problems at all. Just a regular startup where the light comes on for about 3 seconds at start to do a self check, then turns off.
Then about 2 months ago (Dec. 2010) I noticed that on startup, my starter was a little slower, weaker than normal and the startup took just a tad longer, kinda like the battery was starting to get weak and go bad. Though nothing of it. Well, wouldn't you know it, the airbag light came back on after a week or so of that weak starting.
So, bought a scanner and tried to clear the code but it kept coming right back (code 17931). Checked cables, connections, and everything. Dealer told me my airbags had "gone bad" and i needed to replace them but i didn't believe that. I kept putting it off but finally checked the battery and, sure enough, battery was bad, only making like 12.4 volts.
So, replaced battery yesterday (Feb. 2011). And, again like magic, the airbag light has turned back off, all by itself after about 10 starts with the new battery in. No code clearing or anything it just cut off like normal.
Needless to say, this airbag light thing might be affected by the voltage in the system, not enough/too much voltage, airbag cuts off because it sees it as high resistance or not enough resistance in the airbag. Just my experience, might help somebody else, check the alternator and/or replace it and the battery.
from Birmingham, Alabama.
Last edited by matlock339; 02-28-2011 at 01:27 PM.