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[V8S]

Hi all - following on from my recent fuel filter change, we managed to do that successfully. As recommended in my other thread, we unclipped the expansion tank to give us extra room, though it was still a major MAJOR struggle doing the filter because of the hoses in that area.

On starting up afterwards, the coolant level warning came on. We realised that we'd forgotten to clip the sensor connector back on, and after doing that I started it up and no more warning.

However, a few days later (and having driven it to work and up the motorway), I now have the warning back on every time I start up. The level of coolant in the expansion tank is fine - in fact it's now very slightly (1mm) above the cold arrow after I topped it up last night. The sensor connector is definitely clipped in correctly.

Car is a 2.2 DTi Elite saloon.

How does the sensor work?

It doesn't measure the amount of coolant vs. water does it? I can't imagine that to be the case.

Is the level sensor prone to failure? It seems weird that this should happen a few days after moving the expansion tank.

Is there a way to check the output from the sensor?

Can I put a multimeter between the sensor and the fuse to check the wire is ok?

What voltages does the sensor output?

Are there any things I should check?


Thanks very much for any help!

[Andy B]

If you short out the plug on the loom & that 'fixes' the fault, then that would suggest that the loom of the car is OK & it's down t the expansion tank. The magnetic floats do stick & cause problems, but I'd have thought more applicable to older cars. A good clean out with a little caustic might help for a while although a new header tank isn't too expensive. The sensor is a simple open or close switch.

[Markjay]

...although a new header tank isn't too expensive...

...around £30-eesh from Vx and it comes with the coolant level sensor inside. You also get to have a nice clear expansion bottle as opposed to the dark-brownish one you probably have now.... though sadly it wont stay clear for ever....  

[ians]

I have read on here that you can destroy sensors by 'careless' filling of the tank (which I think means missing the hole and getting the sensor connections on the outside of the bottom wet.

My Elite has thrown that error up since I got the car - I have disconnected it (although don't recall having to short it out - may have done though).  In time I may get around to getting a new tank.

[Big_Al]

Had the same problem with my 3.0 Elite.  Coolant level warning comes on but no coolant loss  - it has done it since I got the car 2 years ago. Sometimes it  does not happen for a few days and then returns.

Was advised that it was almost definatley the float sensor in the tank. I just used the re-set button on the stalk to cancel it

Have just recently changed for another header tank and everything is fine now. Has not come on at all

[tanker12uk]

Also had the same problem on a 99 3lr Elite did the cancel routine on the stalk untill I got fed up with it local gm agent supplied a new bottle 5 mins to fit end of problem and yes it is nice to see a clear clean bottle

[Entwood]

Some folks have had success by "de-scaling" the inside of the bottle with kettle type descaler chemicals .. BUT DO THIS OFF THE CAR ... if you decide to try it ....  for £30 odd I'd go for a new one