Hi all, well the red water warning has been flashing up at me and binging for almost a year now despite the engine water temp being spot on and its time to hopefully sort this out once and for all... 

 

I have changed the expansion bottle twice now, once with an almost new genuine bottle and then with a generic copy bottle from fleabay, STILL getting the warning light come on... read some more and others suggested the temp sender, so despite it being rock solid and always reading the same bang top dead centre, so changed that admitedly for a generic sender which does read slightly cooler so little its not worth worring about... I am STILL getting this warning light.  NO CODES SHOWING UP, I have scanned it with VCDS.

 

My next move would be to change the water within the system in case it has become somehow contaminated enough to confuse the sensor probs within the bottle ??

 

Its now beginning to annoy me that all the usual suspects have been changed yet I still have the issue....

 

On another subject my external temp reading has always dropped and then eventually gone back to the correct temp so I've always assumed that there was a break in the cable for that one... but that does not worry me, I can feel if its hot or cold...  however I am wondering if this could be the same issue with the warning lamp...

 

ANYONE HAVE A WIRING DIAGRAM TO AID MY DIAGNOSIS FOR THIS PROBLEM...

 

I'm located in Bristol but do get around, ie this weekend I'll be in Bognor Regis area, if anyone knew what to look for, obviously in exchange for Bank of England gift vouchers (cash).

 

ANYONE .....  ?? 

Pin 1 of expansion tank sensor connector to pin 35 of a 36-way connector at the cluster

Pin 2 brown/white wire to 'Earth connection (sender earth) -1-, in dash panel wiring harness'

 

If you short the connector with a piece of wire, you should get no warnings.  Try it and see for a few days. If you still get warnings, there's a wiring issue or connection problem. If not, it's the tank/coolant.

 

Edit: Oh, and you might be better off putting the original coolant temp sensor back in, a little lower on the gauge is a lot lower in terms of what it's telling the engine ECU etc.

Edited 20 March, 20197 yr by Wino

THANK YOU.... so much for your kind advice and help with the info...  Since changing the sender things seem to have stteled down and I have now done over 1k miles with no further warnings, HOWEVER, I did also try to find the second sensor around the back of the vac pump area somewhere according to the manual !  and possibly wiggled any wires that maybe there so could have cleared any loose connection there ( a possability).  Anyway either way no red warnings since and even the temp gauge / sender seems to be more consistant now also...  despite no codes being generated perhaps it just needed a few cycles of the ignition to clear things down ???  either way NO red water temp warnings for a few weeks now...  NOW if ONLY I could find the break in the outside temp sender....lol.