I live in the U.S. I have a 2013 XJ. 3.0, recently my coolant level light came on, i topped it off and a few weeks later it came on again. I topped it off again. I am not seeing any coolant on the ground and i don't see any evidence of a leak, and the car is not running hot. Coolant has got to be going somewhere, right? I have checked my oil and coolant caps. I don't smell or see anything weird. Anyone know what's going on?

 

After a cold soak, preferably overnight, use a cooling system pressure tester to pressurise the system to 1 bar and check for leaks. The cause of the leak(s) on the AJ126 must be determined as catastrophic engine failure as result of failed head gaskets is the result

The underbody tray is going to catch any fluid leaks.

 

twinsbp1, just a little trick that should work for you. Most coolants have a special dye that will glow if put under a black light. So, when it gets dark, get yourself a black light and shine it in the engine bay. Where you see things starting to glow, that is probably close to your leak. Odds are, you are looking at something around the water pump, this is easy to see. Granted, could also have a leak on the back of the engine at the crossover pipe. You have to pretty much climb on top of the engine and then shine it down behind the engine with the engine cover off.

Like was mentioned, the cover under the car catches a lot of the small leaks and holds on to them. So, it will make finding a small leak hard.

One word of help that I think most people here will recommend is converting the key pipes over to the aluminum ones. Yes, it will cost you $400 for the new pipes and if you pay someone to do the work, probably another $700. But, this will make your car almost bullet proof. The plastic piping that they put on the engine will get brittle over time and develop small cracks and in worst case situations, just completely fail, draining the coolant system in seconds. I am not trying to scare you. BUt, trying to put out information that you should be aware of. There are lots of posts here about the upgraded pipes. For you, the big thing is making sure you get the piping for the 3.0L motor. There are a few different kits out there, so, get the correct one.

 

Good advice from Thermo above! Be sure and take the engine cover off before you start chasing leaks.
Don't ignore his metal replacement pipe suggestion. That's the number one problem with late model Jaguars. Cooling problems.
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It's "something else".
I had the same issue. In the morning, with a cold engine at start up, the warning light would go on. It turned out there was a float in the expansion tank that was failing. It would sink when the coolant was cold and "float" when it was hot.

The float.

The tank with the float inside, needs to be replaced.

 

Hooray! Easy fix. Much easier than pulling the blower off and replacing the water manifolds...

 

Yes. We couldn't find any leaks at all. My 2019 XJL had under 20,000 miles on it at the time.