Maybe there's some difference between our cars. Towards the back of the cylinder head of my engine (OM606), there are 2 coolant temperature sensors. One 2 pin sensor, which I *think* is for the dashboard gauge, and one 4 pin sensor, which I think is for the pre-glow system. Perhaps thers something missing on my car, because it looked like you could put the 4 pin connector back anyway you liked.