To all - I am having an issue with the Coolant Low Warning light coming up time to time on my 2000 Jaguar Vanden Plas with 60K miles. Basically the situation is this, when the light / warning comes on, I check the fluid level and looking in the cap it seems to be perfectly fine. Also the temp guage stays right in the standard area with no signs of overheating. The light / warning will then cycle some on and off. Some days it just stays on, some days it never comes on, and some it cycles on and off when driving.

One thing I have wondered about is it has gotten colder and I started using the heat about the same time this issue popped up.

I am wondering if maybe it is a faulty sensor or something I am not thinking about - any thoughts would be welcomed.

 

More likely a stuck float in the overflow bottle -- lots of threads, here, on this issue.

Temp sensor sticking usually causes starting issues when the weather turns cold. Lots of the threads

 

I got this red light warning on my 1999 XJ8, 7 years ago, my engine has never run nothing but cool. A mechanic shut the light off, but In my non expert opinion it’s nothing to worry about

 

My 00 8L throws the light occasionally as well. I've found the sensor, at least in my car, to be very sensitive. I can remove the cap when the light comes on and it looks full but will take 4-6 ounces of coolant. No idea where it goes, but it does that every 10-12 months.
I don't worry about mine. Just another quirk of older British Royalty...
-Steve-