My darling spouse decided to do me a favor while I was out of town and got the oil changed at a Lube Stop (I bit my lip and did not go frantic because she meant well!). The car was taken for the oil change and driven back to the garage and sat until I got back. Ever since the oil change, I have been getting an intermittent "low coolant" light but I can't find a leak. I checked the fluid tank and the fluid level is right where it always sits.

What could have happened during the oil change?

 

As you probably know by now, the plastic coolant overflow tank is very fragile once it gets some age on it. The guy who changed your oil may have inadvertently bumped it and cracked the hose nipple. Look carefully - it can be hard to spot....

 

Yeah, but if the level's OK..... don't see how any crack either exists or could be causing the light.

Er.... really sure it's the low coolant light? (grasping at straws)

Disturbed wiring/connector would be another possibility.

 

It says "Low Engine Coolant"

I let the car run for about an hour and put white paper on the ground in the garage. I looked around the tank as much as possible. I can't find a leak anywhere. I did do a search on "coolant leak" prior to posting and found the tank is prone to leaks.

Given this car's electrical history, I am going to take the tank out and see if the connection on the sensor is bad. Is the fluid level sensor separate or built into the tank?

 

I have the same thing ("Low Engine Coolant"). The coolant level is perfect, the temperature gauge is perfect, and there is no leak. Also, when driving the light will occasionally go off, then come back on. I am 99% sure it is either a bad sensor, or a bad connection somewhere else.

Please keep me posted on how your explorations go.

Thanks,
Dave
2005 S type 4.2

 

At some point mine also start displaying the low coolant message when the tank was indeed full. I chalked it up to a bad sensor and jumpered the harness it to turn off the stupid message. Later I had to replace the tank (which came with a new sensor) and I re-connected the harness to the sensor and all was well again. Bottom line... I think the sensors do go bad sometimes.

 

Bert you may be in luck if its just your sensor. I am looking at my "old" one that is still on my work bench. I am coming up in a few days and I will pack it for you it is fine and working. Joyce had the case of dripping nipple failure a few weeks back ! Its very easy to replace.

Lunch or cocktails this time?

 

Thanks Rick! I really appreciate it.

 

Bob, can you expand on "jumpered the harness it to turn off the stupid message"? Not sure what that means. Thanks!

 

Certainly. I just bent a very small piece of wire into a U shape and inserted it into the connector that attaches to the sensor, effectively short circuiting the connector.

The coolant level switch appears to be a "normally closed" type (i.e., closed circuit when coolant level is OK), so if you connect the two sides of the contacts in the connector, you trick the car into thinking the coolant level is OK by closing the circuit.

Hope this makes sense.

 

Bob I would advise against this as you could have a major engine failure if there was an actual total loss of coolant. Its OK to do for testing purposes only, but not to remove the light. What actually fails is the float in the coolant expansion tank...not the sensor ...the float gets saturated over time falling to the bottom of the bottle and giving a false reading.

 

EdK: Good advice; however, Bob Smith has not been active on the forum since March 2013. BTW, the sensor is not listed as a part separate from the expansion tank/reservoir by Jaguar. The individual part is available, however, for a Land Rover of the same era. I got mine from Rimmer Bros.

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