My D3 is now in its third alarm siren, I replaced the first one with using a secondhand one from A8parts. The second one failed also after a couple of months, now on my third and touch wood this has been fine so far.

The leaking batteries can cause all sorts of weird issues, as the acid leaks onto the main PCB and eats/short circuits tracks along the way.

Disconnecting the siren seems to stop the car going fully to sleep, so you need to sort this sooner as you'll be getting excess current draw with the car left alone.

Although less prone to battery issues, the D3 which uses the later alarm sirens is not immune it seams.

That's brilliant thanks, I'm quite familiar with vcds but a bit rusty as iv just jumped ship from bmw and inpa/dis, it's nice to have data logging back with vcds as its not available with inpa and makes problem solving on your own very difficult :-(

If it is the same part as a D2, a new one cost me £102 back in October. Plus another £57 to repair the mullered/corroded plug as the battery acid had eaten the terminals AND the plastic plug! The wiring on the D2 is ridiculously short so I bought 3 repair wires and a new plug and had my local indy make the joins as it really needed 2 sets of hands.

Mine did the 3 chirp on ignition on twice before i replaced it and it was already way too late....

I don't think it logged a fault code, but if it's going off it should record what the trigger was, unless the unit is shorting and setting itself off?