I have a 2006 XJ8 that's showing a coolant level low warning even though the expansion tank is full, just like some others have posted. I have taken out the tank and cleaned it out and the float seems to move about freely. I also saw a tip somewhere else that said that too much water in the coolant could keep the float from floating. After removal, cleaning, replacement, and refilling coolant to level, the warning was gone...until about 15 minutes later. Could this be the sensor that needs replacement or the tank due to a possibly faulty float?

 

Check the wiring harness plug, located in the inner guard for corrosion.
Also check your earth point

Cheers
34by151

 

Expansion tank with sensor is cheap. Replace it. https://www.ebay.com/itm/NEW-Overflo...CMake%3AJaguar

Both S-type and XJ8 use the same expansion tank.

 

Done it twice since I've had the car, just hoping it was something else.

 

annamiata, done it twice since I've had the car(cracked nipple), was hoping it was something else simpler, less costly.

 

Do you still have the two old damaged expansion tanks. The sensor can be remove and replace with one twist. I keep junks like various sensors when I visited junk yard or have old parts lying around in garage.

Also, you should on the heater at full blast when change coolant. This will circulate more coolant into the system due to air void. I had the same issue with sensor low coolant and had to bleed coolant several times to completely fill the system with coolant.

 

Thanks for all the advice. Tried all of the above, everything looks good, but still have the coolant low warning on. I also disconnected the sensor thinking that if basically there's "no sensor" due to it being disconnected, then how can it detect low coolant and send a message to put out the low coolant warning. It still came on. Any more thoughts?

 

By the way, annamiata, the first tank was gone years ago and I just tossed out the second one a couple months ago while cleaning the garage. Didn't think to keep the sensors. Damn! But appreciate the tip.

 

Loss of sensor input is probably the safe default mode displayed as "Low Coolant".

 

Another observation is that I can always remember that the coolant level was always correct when nothing was going wrong, but now, whether the car's been running or not, it's to the top of the expansion tank on the left side even if there's little to none in the right side. Thanks for all of the tips, but nothing has worked so far. Hoping maybe replacing the expansion tank will fix it.

 

"it's to the top of the expansion tank on the left side even if there's little to none in the right side. "

It does sound like a new tank will fix it IMO

 

Thanks meirion