The last few mornings it has been really cold here in Chicago, and I have been awakened twice by my 2000 S-Type blowing its horn and flashing its lights, but there is no miscreant about attempting a burglareous entry. I unlocked it with the remote and went back to sleep. Thinking about it, I remembered that, while driving, I have occasionally seen the words Boot Open on the message panel when I hit a bump, but then it goes back to Miles to Empty Tank. Eureka! The theft alarm was being set off by the trunk light switch when it got really cold. So I pulled down the cover panel of the trunk lid and found the switch bracket is held on by only one bolt, and the bracket is rather flexible and was bent upwards. I bent it downwards a little bit and that seems to have done the trick. But I think the bracket should have been either stronger or held by two bolts, something to look into when it gets warmer.
Hi Rob, I had a similar experience with my 2003 S-Type, but it only happened spring and fall, when cold nights warmed up around 9 am. In my case, the message was ‘passenger door open’ It turned out that the sensor in the door latch mechanism was at fault, and the door was in fact locked. The fix was a new, expensive door latch.
Mike
The sensor is a microswitch in the front door locks and with care, they can be replaced which saves the cost of a new latch. I have done a write up on how to do this but I can’t see a way of putting things in library any more.
Eric