I have exactly the same issue on my '90 XJ-S Convertible V-12. The warning light is on all the time, despite the fact that the reservoir is full. I was going to dive in and just change the sensor, maybe I should wait to see if anyone out here can help.
JK
Hi,
>
> I have a 1991 XJS V12 Convertible. Recently the Coolant Level Warning Light
> started to come on. The Coolant Level was ok, and I've had the sensor
> replaced and the system pressure tested just in case, but the light still
> flashes on intermittently. Anybody any ideas please?
>
> Cheers
>
> PeterB
> 1991 XJS V12 Conv.
> 1998 XJR8
>
>
>