i am well aware of the colour coding aspect i didnt plug the yellow to brown, the car is a bit of a dog and im slowly getting it to run better for my workmate, the guy he got it off had tampered with the meteringhead and the cold start valve had the black connector attached, this car has temp sender(green) in correct place, aux air valve(black) now in correct place and cold start(blue) in correct place, then there is tts valve(brown) with a yellow plug, there is no yellow senders nor is there brown plugs??? when you unplug the yellow from the brown the car runs like there is no boost?? rs manual i have for my s1 does not have a yellow?? so either some bawbag has minced up wiring somewhere or there is a yellow sensor wi a brown plug. any one know what happens when you disconnect the thermo time switch. cheers