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 FAQ #136
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Fix a C4 Coolant Circuit Level Too Low - False Warning
I've got this warning coming up intermittently whilst driving. I've checked the level and topped it up to Max, so it must be a false warning??

robbie-rocket-pants wrote ...

After driving around with the sensor disconnected for a few days there was no more recurrence of the fault warning so I concluded it was not a wiring short and the fault must be with the sensor.

I then set about fettling with the sensor:

1. I syphoned off the contents of the expansion tank (about a pint)

2. Turned the sensor through 90 degrees and wiggled it out of the expansion tank

3. I noticed 2 prongs on the sensor which I presume must allow a small electric current to flow when dipped in the coolant, but instead of being shiny metal they had a coating on them (oxidation maybe)

4. So I got a bit of sandpaper and cleaned the prongs back to shiny metal

5. I put the sensor back in (starting at 90 degrees then pushing and turning), re-connected it, re-filled the expansion tank and hey-presto !

Fixed for tuppence ha'penny.

Hope this helps someone.

Cheers, RRP.

Here are some photos.

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FAQ Posted by robbie-rocket-pants
Info Created: 01 April 2009
Last Updated: 19 January 2010