X Type alarm going off

[Ricky7774]

Had my low mileage 2006 x type for 6 months then, as it was parked in the sun, decided to get a front windscreen sun shield, one of those fold up ones that you put against the inside of the windscreen.

First morning after I used it, the alarm went off for no obvious reason. Four days later, same time again. Both times when the sun was blazing down. First one at 09:30. Second time at just after 10 am.

Checked in the handbook and as I assumed a possible faulty sensor, decided to lock it on the key once, which is the way to lock it if you've left kids/dogs in the car as the movement sensors won't set the alarm off, according to the handbook.

All was okay for a few weeks until the alarm went off again twice in about a week. On these two occasions I'd parked the car in my secure back garden facing the other way, so just left the sun screen folded across the rear seat.

The 4th time it went off was 03:50 in the morning so decided to get it checked out.

Whilst waiting for the diagnostic appointment I purchased an on line Jaguar manual so I could check out the alarm system. Boy, does it have a lot of alarm sensors!

The critical one was the intrusion sensor which is in the interior courtesy light housing by the front screen and the internal rear view mirror.

The sun screen protector I bought was laminated on one side but the other side, that faces the inside of the car, was backed with metallic foil. That made me start to think that the foil could be setting off the alarm in certain sun light or lighting conditions so I removed it from the car. Two weeks so far and it hasn't gone off again..... yet. The diagnostic test showed no faults with the alarm and the garage guy said the foil could have been reflecting the microwaves that the sensor bounces around the inside of the car.

Not sure if anyone with alarm knowledge can verify this theory, but worth giving some thought if your alarm has started going off to see if you have put anything in the car which you didn't previously, and if its metallic, it could cause the alarm to sound.

It might have just been a coincidence that the alarm became faulty the day after I used the sun screen for the first time. I'll only find out if it goes off again.

I'll keep you informed if that happens but if I say nothing further here, you can assume the fault has not returned.