well i just bought a 2013 jaguar xf with the 3.0L supercharged engine. Wife loves the car but she is getting this warning message every day. I checked the coolant while cold and added to the "cold fill" line. Warning still coming on. I have heard that maybe the float inside the tank could be stuck or maybe a sensor? How do i check the float? What is the best course of action to get this corrected? Thanks!

 

If the dash warning keeps coming back it is not a good sign. It is time to hope for the best and prepare for the worst. It could be the plastic coolant bottle degenerating (see picture), radiator cap losing pressure and hence water lost through vaporization, one or more water hoses breaking, water pump leaking, etc. The first thing to do is visual inspection of the car to find any water strain or water drips while car is running or after stopping the car for a while. The first place to look is the bottom of the coolant bottle. The other conventional diagnostic method is to let a workshop conduct a water pressure test and trace whether there is a leak and and where it happens.

 

Just to clarify. Is the coolant level going down? Or did you just top up once?
If it’s going down and you have to keep topping up then clearly a leak and I agree with the above. If it’s staying full but warning light is on then prob the float stuck, switch not working etc. and much less serious!

 

If the coolant low message is a false alarm (but always pays to check) then it's probably the float sensor. Similar thing reported with the Land Rover/Range Rover which uses similar parts - the float becomes porous and stops floating properly. The float is part of the coolant overflow reservoir so replacing the reservoir should fix it as you can't buy the float sensor alone. Other enterprising souls have added little poly flotation devices from CD stacks to the sensor to help it swim...

 

I would pressure test the system first. I looked for a leak for hours, finally i gave up and rented the pressure tester from autozone. Found the leak in five minutes. Fixing it is another thing..lol

 

On the overflow coolant tank, when I top it up on occasion in my 2001 XJ8, how high should the coolant level be? I leave it maybe an inch or so shy of the top.

Too high? If it is spilling out under pressure, I dont see any evidence of it. A pressure test didnt show any leaks. Thermo, pump and thermo housing have all been replaced over the years.

But back to the level, how high is right?

 

I have a 2011 XJ supersport today the coolant level low warning came on. This was following an emergency stop. I cycled the ignition several times after but the problem has remained.
Having read multiple forum posts on the subject suggesting replacing the tank and sensor I figured I would try the simple stuff first.
Given that the coolant level has not changed in 3 years of owning the car I figured it had to be the sensor. The car does always put out steam from the exhaust when the weather is cool and when examining the steam with my finger and tasting (sounds gross) it is just water vapour and not the dreaded head gasket leak. Water is a bi product of petrol burn so I expect it in a 5Litre engine.
As I did a rapid stop I figured the coolant had shifted to the front of the tank and set off the sensor. Maybe as I stopped on a rough country road maybe it was jolted and got stuck.
I waited for the coolant to be cool enough to remove the tank cap and inspected it. I considered poking a pipe in the an blowing some air in but lack of a pipe I resorted to giving it a bit of a Clarkson. I started shaking the tank and gently banging it and also gave the connector a wiggle and checked it was connected properly. After a minute or two of tapping the tank and shaking I put the lid on. I turned on the ignition and the warning light had gone.
I would suggest giving it a good tap and inspection and maybe having a gentle probe if this fails before it becomes and expensive fix.
I did note the coolant does smell a little hot or burnt but it's colour and condition coupled with the way my car runs would suggest this is probably normal after 25k miles. It tasted as it should and will get a flush as dictated in the service manual.
I know my problem was just caused through an extreme driving situation but it should still be considered if the problem arises. I would also take note that when freeing the stuck float the coolant was close to operating temp so may of made it easier to free off.

 

dang
my '12 xf v8 just started all this..
knew it was tgtbt to not have something go wrong..
my level was going down and topped it off several times and its been running hot. have got the coolant low only once topped off and went away

cant see or find a leak... so where would it go?
i have the full extendend warranty, would that be covered? read the jag website and said collant system is covered but yea who knows...

also would it be advisable to drive it to the dealer(close to 200 miles away) or have it towed up there?

thanks

 

I got a 2012 XF portfolio I was wondering ​​​​​​If the coolant tank float is stuck. How can I get it loose so my coolant low light won't turn on? I changed my level sensor and have no leaks recently fixed any coolant leaks by changing out coolant hoses and plastic lines. I know my coolant tank float is stuck I was wondering if anyone knew how it get it unstuck so I won't have to buy a new tank if possible of not aubviosly I'll buy the tank . But any knowledge would help me and future readers of this forum.. thanks lmk

 

They are plastic and are a wear item. So I would plan on replacing it. Remember your car is now about 12 years old and all the rubber and plastic are pretty degraded at this point.
One suggestion is the two front coolant pipes are a problem and I really recommend going to the lifetime aftermarket Aluminum ones. That fixes what is the worst problem on these cars. But if you have changed them out with the old style plastic ones keep a close eye on coolant levels.
.
.
.

 

Thank you for your post. I had this problem, on my XF and followed the instructions here. The important post was 'the emergency stop' message because I too had an emergency stop some 20 minutes before the error message appeared. I 'wiggled' the sensor, the tank and float and the problem is solved.

Brilliant!