I bought the 2000 XK8 last summer. Presently has 43K miles on it and is doing great. Today I had a strange thing happen. The low coolant light came on for a very short time and then went off. Didn't come on again. When I got home I checked the expansion tank and it was a little low but not much. So I added a little coolant. Then I checked to be sure the sensor was connected. And much to my surprise it was not connected. In fact it had never been connected the whole time I had owned it. The plug end was taped over to protect it. I have two questions. How did it work without being plugged in? And, since there has never been a problem before leaving it unplugged should I just leave it unplugged? I keep a good check on the coolant.

Thanks guys.

EZDriver

 

All you have to do is 'jump' the wire side of the connector to advise the ECM that everything is wonderful. There was probably a 'GEM' clip or a small wire connecting the ECM side of the connector to eliminate the 'low coolant' warning.

A functioning low coolant system is a nice thing to have as overheating an aluminum engine can occur in a very short time.

 

After removing the tape I see what looks like two wires twisted together. Looks like one of the previous owners had a problem with it and grounded it out. Think I'll get a new sensor and replace it. Not sure how it attaches to the bottom of the tank. I think my 95 XJ6 has the same type sensor. I'll look at it.

Thanks Test point

 

The sensor 'snaps' into the bottom of the reservoir and a blade screwdriver can gently pry it out. Careful, the sensor can be easily broken. I know. I would even suggest that the tank be removed to replace it.

The sensor is activated by a floating 'donut' magnet around a hollow tube. Coolant gunk can cause the donut to stick and give erratic low coolant warnings.

I recently replaced my reservoir with an OEM one and found that the sensor had been glued into the tank. Guess Jaguar does not want the sensor changed in the future without tank replacement.

 

Thanks Tom for the info. I checked my XJ6 and the sensor snaps in that tank also. I need a new sensor since the one I have is trash. I'll try to get one from Motorcars Ltd in Houston. If you have a better source I'd like to know it.

Thanks

Bob

 

They are not real expensive, I bought one new off eBay for $12 if I remember correctly.

 

Thanks Tom for the information. I did get a new sensor and snapped it in with great difficulty. I didn't completely remove the tank, but enough to gain good access. I fit good and there was no warning. A few days late my wife took the car to a function about 30 miles away. It lasted about 3 hours. When she started home the low coolant warning came on and she pulled over and stopped right noe. Called me on the cell phone and I coached he to open the hood and open the expansion tank. She did that and said it was almost full of fluid. After she got home I checked the sensor mounting and everything looks great. Good installation, new sensor, plenty of coolant and warning light on. Not sure what to do now. Got to think about it. Any ideas are welcome.

Thanks Tom

Bob Sudderth

 

"Coolant gunk can cause the donut to stick and give erratic low coolant warnings."

For what ever as yet undetermined reasons it is not unusual after a few years of service for the donut to hang up on the hollow tube that encases the sensor. I had exactly the same problem a few years ago and cleaned out the reservoir with soppy water and then a good spray of brake cleaner on the tube/donut. That seemed to fix it until the reservoir started leaking. I tried JB weld which held for more than a year and a half before I gave up and replaced the entire thing. Your car is now 12 years old and subject to such strange issues.

"The thing is not broke until I take it apart for the second time and cannot fix it."

Badkitty posted a great quote recently that truly applies to these cars:

"I have come to understand that owning a Jag is like owning a horse. There's no joy in it unless you love taking care of it."

 

A lot of good quotes. And I have to agree with every one.

However, it did work for the 30 miles to her function. Then failed on return. I talked to Ken and he is going to check if there is a way to test the sensor when it is out to see if it is faulty. He said that failures of the sensor are not uncommon.

Right now I have the connector shorted out to get rid of the message.

Thanks Tom