When the coolant level in my 04 XJ8 gets only about 1/2 an inch low the "coolant low" message comes on. It happened today. I added maybe a cup of coolant to bring it back to the full mark. I can find no leaks. Seems overly sensitive to me. The light comes on way too soon. Plus the sensor is still fully submerged. Does this happen to anyone else or do I need a new level sensor?

 

There are number of threads re the float getting porous, so it sinks too easily.
Have a search around and post back if you're stuck.

 

Thanks didn't realize it used a float.

 

I found the float thread. My tank is only about two years old. If my problem was cause by a sinking float then adding a cup of fluid would not make it float again and extinguish the warning. I will be upset if this relatively new tank has a submarine float!

 

Happens to me, too.

 

If it continues to do that I will jump the sensor. A sensor that cries wolf is useless. I am not about to buy another high priced junk tank.

 

I'd be a bit wary about doing that since the delay between a real 'Low Coolant' message and buying a new engine is, apparently, extremely short.
Have you checked the magnet hasn't slipped ?

 

Mine does the same thing. I was told an easy cure was to remove the tank and shake it gently while part filled with CLR (if you have that product,it removes scale etc) mixed as directed. Haven't done it yet but!

 

Mine did it again this morning. The last time I got the 'low coolant' message was about 4 months ago, and all I had to do was add a splash. Good for 4 months. Same story this morning. It's a little annoying, but I can live with it happening only once every four months or so.