Audi TT alarm

[cjb44]

The alarm keeps going off on my 2009 car, have checked all doors and the boot are shutting correctly, but still happening. For some reason, the spoiler came up without using the switch although I got it to return by operating the manual switch whilst in neutral with the engine running. Currently, I am having to leave it unlocked, any ideas chaps?
Thanks.

[Belle427]

Maybe look at water ingress, I’ve no particular experience in your model though sorry.

[Nickbrapp]

Bonnet sensor, common on Vag stuff. Water gets in the contact.

[cjb44]

Thanks for the replies, taking it into my local garage for them to use a diagnostic reader and see what comes up. Also, I had to use the key in the door lock to kill the alarm since then the fob does not work, I imagine the synchronisation has been upset but following the manual has not helped, and yes the battery in the fob is OK.

[cjb44]

UPDATE
The alarm is fixed, for those who are interested here is the sorry tale.
Contacted various mobile companies, mostly uninterested some who made appointments never turned up and when contacted I got the old "Sorry mate I am very busy", so decided to take it to a local BMW/Mini independent who assured me they would fix it. Having scanned the car and checked the wiring for breaks/bad connections they found there was some evidence of condensation on the control unit mounted in the boot, which was dry so not water ingress (they showed me the part). they replaced this unit (Audi supply only) it would seem they were right as both keys now work and the alarm is silent when not activated by movement etc. I am now £976.00 lighter, but in the end was less of a drama than chasing key "jockeys".

[E63eeeeee...]

Ouch. But at least it's sorted.

[FMOB]

This is usually the backup battery in the siren falling, this causes the alarm to go off at random.

As for diagnostics, the siren usually doesn't support any sort of remote diagnostic. Last siren I bought was around £80, your fault sounds more significant but on a 2009 car I would tried swapping the siren first.

[cjb44]

That is interesting. Where is the siren located and is the backup battery charged by the car during driving as per the main battery or is it replaceable?

[FMOB]

Not sure about the TT but when I looked for it in an A4 it was buried right hand side of the boot deep down.

The batteries are charged by the car but on a 2009 car they are at least 10 years old and do degrade over time, if water gets in the siren that will damage them.

[cjb44]

Thanks for that, it currently is behaving itself, so I guess the answer is to wait until it goes wrong again. Meanwhile, I now have to battle with my wife because she is making noises about not trusting it and should she part exchange the car (typical panic mindset)
I told her it will be fine, and as the car has only done 50,000 miles and is virtually mint, she should at least get some value out of what I have just spent; however, it is her car so time will tell.