2010 XF Supercharged has a perpetual low coolant warning light. It is fully topped up and the sensor was replaced.

Any ideas in how fix it?

 

My garage is on a small slope and I get the low coolant warning every morning. Once I drive for a block or two it goes away so I haven't worried about it. Sorry I don't have more to add.

 

Has it been "burped"? An air bubble in the system could be tripping the system.

 

Yes it has been burped. There is no slope in our garage and the light never goes off.

 

Really weird situation. I'd have thought the coolant level sensor would have sorted it.

Could a hairline crack in the top of the expansion tank cause this (where coolant loss would be minimal but somehow the air getting in is triggering the low coolant warning)? Just thinking out loud here.

 

After a few on and off low coolant warning messages spanning several weeks, and checking the coolant level often, the dealer determined the water pump needed replacement. Up to that point, it was a mystery. Good luck, but keep an eye on the water pump - it will usually make some loud rumbling noises as a warning.

 

Alright, I'll let my dad know.

 

I had the same problem for weeks. I was told I needed a new water pump. Once they got in and started removing parts they said a number of the plastic lines front the coolant reservoir were starting to deteriorate (pretty common for 09 / 10 sc and xfr) the leaked just enough where it dropped the levels but slow enough I never saw anything on my garage floor. Id lead with the water pump replacement since its relatively inexpensive but ask them to check the coolant lines. I imagine one or both are causing the problems and both are know weak points in the engine bay. If your car is out of warranty Ill hope for fuel pump as it looked like swapping that out was about 1/4th the price of the coolant lines. For me work was done under warranty but wanted to see what long term cost of ownership looked like when the warranty expires next year.

 

Well, sounds like the sensor is still not working even though you replaced it since the coolant level is not low. It could be a wiring issue or a bad replacement.

All these suggestions to fix a leak aren't going to help you if you aren't losing coolant.

You could test the sensor with a volt meter, but I don't know what are the normal voltages for low and ok fluid levels. You'd have to look that up in the manual, or check it on a car you know works.

 

We don't have another XF available to us to check. I doubt the sensor on my XK8 has the same volt measurements.

 

See if this helps.
https://www.jaguarforums.com/forum/x...-123539/page2/