I have a 1985 Regal, it's a 6-cylinder, automatic. My check water temp light came on so after checking my coolant, water pump and finding nothing wrong I changed the tempature sensor and nothing changed. I replaced the sensor with a gauge. It screws right in to my block. Now my service engine light comes on after I drive it a while. If I shut off my car and restart it the light stays off for a while again. My temp gauge reads 170 degrees to 190. Do I need to hook the sensor up for any other part of the engine to function correctly or is the light coming on because its unplugged from the sensor?