This has been a consistent problem for me that I finally have the time to fix. The only problem is I am seeing dozens of stories about this but none really compare.

For starters:

- I don't believe it is an interior motion sensor issue as the windows are always up when parked.

-The alarm goes off when I am driving.

-The key fob has never been programmed to it, as I have never had two keys to set the fob. Since purchasing a second key, I have retried recalibrating with no success.

The system starting blarring like this when my battery started dying, maybe two months after I bought the car. Prior to the battery I had no issues, but ever since replacing the battery, the system has a mind of its own. If I am driving it, or letting it sit for about 5 minutes causes it to go off.

I also noticed at the same time, the 'Trunk open' warning light is constantly on. At first, the warning wasn't present until I disconnected the fuse.

I have read about this being a factor in the S4 when the locking system acts up. Or is there a trunk lid sensor that I am not aware of that could be triggering it?

I have NOT scanned with a Vagcom to the security system, but when scanning the car, no messages appearing concerning the security system.

Thanks in advance.

 

This is a very strange issue, and not one I've heard of before. The only help I can provide: you need VAG-COM to access the appropriate modules. OBDII scanners generally only look at the engine module.

You may just need to clear fault codes to stop this behavior... but again you'll need VAG-COM.

 

Mine does that when it gets hot outside, I just don't lock it.

 

Very odd, that's the first I've heard of an alarm going off while driving. I didn't even think that was possible. OP, where are you located? I have a ECS Master and full vag com and would be happy to scan your car for you.

 

OP here, on my other account.

I live in Wisconsin. And I am happy to see the enthusiasm in here for trying to solve something new.

I just reconnected the rear horn and put the fuse back in. No problems yet, but it also won't calibrate my fob as well as the unlock button on the door will not work.

Though I do have the flashing red lights going off on the door.

 

What year and model is your car? If your ignition switch is worn or the key is worn, it can cause alarm to go off while driving. There is a recall on certain years for the ignition switch....but you really need to get it scanned and get some codes... I've had my hood sensor go bad as well and just set alarm on and off while parked but never while driving...

if you scan it, check the convenience control module, it regulates key fob, door locks etc...

 

I will keep that I mind. And it is a 1999 A4 1.8T

I can't remember if there was a recall for the ignition switch on this year of car.