Hi
Recent development.
When car is idling for a few minutes the red low coolant light comes on. The temp gauge is fine. Right in the middle.
when i let the car cool down there is no low coolant.
Any ideas?
thanks

 

FIrst thing I would do is idle the car until the warning light comes on, look through the side of the coolant reservoir and verify the level is still normal (obviously don't open the cap while the engine is hot). It takes a significant drop in the coolant level for that warning to trigger.

If the level is correct, then it's likely just a bad sensor in the tank. Very common failure on any coolant tank with a level sensor. To confirm the wiring integrity is good, you should be able to unplug the sensor from the bottom of the tank and short those pins with a jumper. That should result in the warning going off.

 

The red light on the temperature gauge is not a low coolant warning, it indicates an issue with the temperature gauge circuit, either no signal, or an overheat. Every few months mine will light up and the temp gauge will not move, but I read good temperature with a scan tool. After a couple of starts, drive, and shut downs it returns to normal. Since I can see the temperature with the scan tool, I haven't worried about it.

An actual low coolant indication is given in the text display on the dashboard, and the sensor for that is at the bottom of the expansion tank on top of the radiator. If you haven't seen the text "Coolant Low" on the dash, then you don't have a low coolant condition.

 

^^^ this. The red indicator at the top of the temp gauge (circled in image below) is not the low coolant indicator, as wfooshee stated. Two totally different things.

Agree with looking at the engine coolant temp value in an OBD scan tool to verify the ECM is seeing the correct temperature and it's within normal range. If it is, then the issue is with the cluster receiving the data and that's a separate issue (also probably couldn't be fixed if it happened in Jaguar factory in front of the team that designed the car). Been down a bit of this road myself... cluster likely has a stored code for "missing coolant temperature data" and doesn't know where to set the gauge pointer. Somehow a message is getting corrupted on the CAN bus from the ECM to the IP.

 

I agree with what the others stated before me, the red light in the temperature gauge does not indicate a low cooling fluid level.

What is intriguing me is that you state that the temperature light comes on, but that at the same time the cooling temperature gauge ist still in the middle. Although the car has a system that keeps the needle in the middle of the gauge as long as the real temperature only fluctuates between a certain temperature band with, it should go up before the red light comes on. My conclusion is that you have a sensor problem somewhere.

If you have a real temperature problem, my first suspect would be the thermostat, although these have a safety system that in case of failure keeps them open, instead of closed.

I would also use a Jaguar specific code reader to see what the real cooling fluid temperature is

Good luck and best regards,

Thomas

 

Gauge is in middle no red light there.
Text says coolant level low with warning light.
coolant level is not low.
must be a sensor.
this only happens when idling for a few minutes while waiting for the wife in the supermarket.
i have another option of not taking here or convincing her to shop on line but then the car would no longer exist.🤣
Thanks again
stg424

 

OK, I misunderstood which light you were referring to, and you meant the light right above the text display.

The sensor for the coolant level is at the bottom of the expansion tank, and if it's disconnected it will default to showing low coolant. It's a simple normally-open switch with a float that closes it when there is coolant in the tank. Open circuit mean low coolant, and if the connector is loose, it is certainly an open circuit.


If the connector is loose, simply plug it back in. If it's connected and still showing low coolant, then it's either the sensor itself, or the wiring from that connector. I don't think the sensor is an individual part, you'd have to replace the expansion tank, but that's the first thing I'd try if it shows low coolant and the connector is in place OK.

EDIT: Just re-read your post, where you said it only happens while idling for a few minutes. That well could be an actual low coolant issue.

Coolant level should be checked with the car level and stone cold. Open the cap and look down into the tank, and you'll see two raised bumps molded in, marked MIN and MAX, and the coolant should be somewhere in between. If you need to add coolant, remove the small hose at the top of the tank to allow air to escape from the engine's coolant passages. Don't forget to reinstall that hose before starting the engine!