coolant temp sensor

[dupek]

I have a 97 golf gti 2.0 and i am having the stalling problems. I bought a new coolant temp sensor, but on my coolant flange there are two sensors one upper and one lower, which one do i need to change?? or do i need to change both?

[rubjonny]

the one with a red/yel wire is the ecu temp senor, 4 pin black and it may have a yellow ring on it. usually there is only 1 sensor though, if there is 2 the 2nd is for aircon but usually that goes in the flange on the side of the head not the front...