I apologize if this is a repeat but the service person at the Audi dealership told me they'd never heard of this issue, and I haven't seen someone explain this yet.

About 50% of the time when I lock my car using the remote, the car chirps normally to signify the car is locked. The other 50% of the time, I'm not 100% sure, but I think my car's panic alarm goes off. I get around 60 seconds of very loud beeping, then it shuts off.

The service person at the local Audi dealership told me it's probably a bad relay on one of the doors and estimated $500 in diagnostics alone.

Has anyone experienced this or know what's going on/how it can be fixed?

 

Issue could be caused by a door pin switch that is faulty. If you arm the alarm and a door is detected open it will cause the beeping.

I believe these switches are built into the lock mechanism in the front, but the rears should be serviceable. Play around with the doors and see if you can pull on the door handles while it's locked to trip up the switch... maybe then you can determine which switch is causing it.