VW 4 wire engine temp sensor

Trying to find some info on trouble shooting 4 wire engine temp sensors on VW's. I don't think Paul talks about 4 wire sensors and I cannot seem to find any info on them here either. Only info I can find about a 4 wire sensor is that the ECU might be taking a Kelvin measurement. What is the best way of testing these properly?

Year model and engine and i can look it up for you to see what each wire does

We'll see what the wiring diagram has to say once we know the YMM, but I'm betting it's just a two wire ECT sensor and a gauge sender combined into one. Being VW, the sensor probably goes into a plastic housing, so the sender has to have its own ground (instead of grounding into a metal housing).

Thanks is a 2005 Lupo 1.4I.

That vehicle isn't in the US. I had to go back to 2000 model year to see a coolant sensor with 4 wires.So I an't really tell you wire colors because yours may be different, but 2 wires is for the PCM and the other 2 wires is for the gauge. Not sure if that's how your car is set up but it probably is. What exactly is wrong with your car?

Thanks for the info. It is someone else's car with a P0118 code, I havent looked at the car yet nor a wiring diagram til Tuesday.

OK. If you have access to a wiring diagram it should be easy to tell whats what. 2 wires will be ground, 1 signal to PCM, and 1 signal to gauge. With the sensor unplugged the PCM should show -40 or so and with the PCM signal wire jumpered to ground the PCM should show max temp, whatever that is in Celsius. 150 degrees maybe, not sure

Thanks again.