Beeping from my a3 help!

[Leroy902]

Hi,
I've had my audi a3 (54 plate) 130tdi parked up rotting away for a year after losing the keys, so I decided to get it roadworthy with the intention of selling it on.
I had a chap come round and got a new key/fob made.
This morning I changed the battery, it fired up without any issues.
It opens/closes as it should, the key/fob seems to do what it's meant, I can pop the boot, lock and unlock it using the fob.
After giving myself a pat on the back and going inside for a cuppa, I noticed an alarm like sound coming for my driveway.

It was coming from the a3. It sounds more like a 'beeping' sound then an alarm and it's coming from the boot area just behind the passenger rear lights.
It seems to stop for afew seconds, then start up again.
If I unlock the car using the fob, it will switch off.

Any ideas?

[Leroy902]

It doesn't have any sort of parking sensors.
As I said I'd spend the the morning changing the battery, would that have any sort of bearing on the alarm? (if it is coming from the alarm that is)

[Leroy902]

gottans said:

Will be a dying battery in the alarm siren.

Is that an easy fix/something I can replace myself, or something I'd need to get done by a specialist?