88, s4, coupe, 13b NA

had to replace the front cover but noticed something shiny staring back at me. anyone know where exactly this goes?

 

Check on the backside of your water pump housing. There should be a water thermo sensor. (It might be difficult to see.) Is there anything plugged into it? If not... That is where these wires go. Those wires are missing the connector. I forget if that particular connector is green or blue. (The connector is a Bosch EV1 style connector.)

 

Yes, dull green water thermo sensor behind the alternator, under it and to the passenger side. Find the BAC valve, follow the coolant hose forward until it meets the water pump housing, and above that will be the sensor.

Car must run poorly without it plugged in, and probably gets horrible mpg. Fix this ASAP!