Ok this isnt my car, its my brothers, so i cant just nip outside and check things.

The code i have is in the first post.

I've got a spare CTS that works fine, so next time i'm over at his i'll plug it in and see if the code goes away.

I guess it could be a short in the wiring. But i dont understand why i've got a perfect readings in the measuring blocks. If the wiring was faulty, or the sensor was faulty in the way that the ECU is describing, it COULDNT provide a reading. A shorted out sensor cant provide a signal.

Which means either the fault code is erroneous, or its real but the ECU is pulling the data from the cluster?



The thermostat issue is a different one, and gives a different fault code. As i said above, there is no "Sensor" in the radiator. its just a switch and the only thing it does it power a relay for the fans. What the ECU does is have a map which says the engine should warm up in x minutes, and once warm it should stay at 90c. With a faulty thermostat, the engine either never warms up at all, or the temperature rises and falls with speed. This causes the ECU to realise something is wrong, and flags an Implausible Signal fault code. This is NOT whats going on with the S4, so please dont try and confuse matters talking about thermostats.