Jaguar XKR alarm problem - no codes stored

[threadlock]

My 2009 X150 (5.0) XKR has an alarm issue: the alarm has gone off a few times for no good reason.

A couple of weeks ago the dealer replaced the two intrusion sensors because a diagnostic code pointed to those as the source, but the alarm went off again. After that they disconnected the intrusion sensors... but the alarm went off at the weekend. This time the computer stored no event codes at all; no problem codes and no "this is which sensor triggered the alarm" codes.

If I single-lock the car, the alarm doesn't seem to go off.

Does a complete lack of diagnostic codes suggest anything useful? The dealer is stumped and I can't find anything on tinternet that gives me a clue. At some point the dealer is going to hand the car back, shrug their shoulders and I'll be on my own (and the warranty has run out).

Suggestions welcome...

Edited by threadlock on Thursday 3rd July 09:01

[8bit]

If single-locking makes a difference then maybe something in the door lock system is amiss?

[Jagslag]

First thing,get the battery checked out.They should be using IDS/SDD diagnostics,lets hope the Tech at jags knows how to use it properly.

[yellowtang]

I believe that turning off the alarm sensors via the touchscreen only leaves them off until the engine is next started. It's a function to use when being towed or traveling on a ferry.

I also understand that pressing the lock button once will only partially set the alarm and that doesn't include the volumetric sensors.

I hope you get it sorted - mine drove me bonkers!

[threadlock]

Thanks all.
I wondered about the battery health too, Jagslag, but they tell me they've checked that. I know these cars are sensitive to this though.
I don't know which diagnostic system they're using; I have to trust them because they're a main dealer, but the front-of-house team do their best to shield customers from the technicians who actually know what they're doing which is a pity. Now the warranty has expired I'll have a bit more flexibility if I want to try other experts.