There is 0.34 to 0.4 volts across the blue/green wire and ground. Shouldn't this be 12 volts or more? and does this automatically point to a damaged wire? With the ignition turned on there is only 1.07 volts across the thin red/back wire and ground, which seems low. There is no voltage at all across either of the thin wires and ground with the ignition turned off. There is also continuity between the thick brown wire and ground, which sounds correct. I have put a meter across the wires and there is a permanent 12v supply across the thick red wire to ground (or the thick brown wire).

The plug has 4 wires as described except the 'thick black wire' in my case is actually a thick brown one. I have disconnected the electric fan plug described in Madtek's previous post. I have checked the engine coolant level, and also the windscreen washer fluid level (which someone told me could be the cause because the w/w sensor and low engine coolant sensor were wired in series).īoth fluid levels seem OK, but should I be testing for correct operation of these sensors too? If so, can anyone suggest how I can best do this and advise where are they located as I can't even see them. When this first happened (some weeks ago now) it started to display the 'Coolant - visit workshop' message. My car appears to be running in 'limp' mode (poor acceleration and revs wont exceed 3K). I've just happened upon Madtek's useful post following a search to understand a problem that I have on my 2003 c200 CDI.

2004 c230 kompressor coolant sensor