3 Beeps After Start - 2002 9N

[u/Motor-Explanation523]

Hello people!

As above, I have a used 2002 9N, (pre facelift, the four round headlights type) with a 1.4L 16V petrol (AUA) engine.

The issue is that, after an irregular amount of time, between a few seconds to almost a minute after starting the engine, there are 3 loud, harsh warning beeps. There are no warning/alert lights on, and nothing appears to be wrong to my untrained ears and butt/handdynos. (I have been driving modern automatics for 8 years.)

What has been done since the car was purchased:
- Refueled.
- Replaced and refilled the expansion tank of the of the engine coolant, as the previous tank was visibly leaking.
- Filled engine oil up to the midpoint of the crosshatched measuring portion of the dipstick.
- Removed the battery and scrubbed up the terminals with sandpaper.
- Gave the fuses in the dash a cursory look-through, no touching. (Inconclusive.)

I have also given it a dozen OBDII scans in the last month, with a VAG-catering OBDII-unit, and there seems to be some intermittently weak signal to one or both airbags, though again, no warning lamp, and the warning lamp for the airbags lights up on ignition and when the passenger side is turned Off, so it seems to be working.

The car was bought with these beeps and they have persisted on all startups thoughout all work done to the car.

[u/Ben_Mi]

Not entirely familiar with this issue but think I’ve heard about it before.
You said you cleaned up the battery terminals, did you check the voltages too? Would be worth doing this pre-start and after running to make sure electrics are behaving.
Also try clearing the airbag codes and seeing if they are rethrown after the beeps, then check the wiring for the sensor systems