Coolant temperature sensor?

ENGINE COOLANT TEMPERATURE (ECT) SENSOR REPLACEMENT

REMOVAL PROCEDURE

NOTE: Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.

1. Partially drain the cooling system. Refer to Draining and Filling Cooling System (LS4 Static Fill) Draining and Filling Cooling System (L26, L32 Static Fill) Draining and Filling Cooling System (GE 47716 Fill) in Cooling System. See: Engine, Cooling and ExhaustCooling SystemService and Repair
2. Disconnect the ECT sensor electrical connector.

3. Remove the ECT sensor.

INSTALLATION PROCEDURE

NOTE: Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.

1. Coat the threads with sealer GM P/N 12346004 (Canadian P/N 10953480) or equivalent.

NOTE: Replacement components must be the correct part number for the application. Components requiring the use of the thread locking compound, lubricants, corrosion inhibitors, or sealants are identified in the service procedure. Some replacement components may come with these coatings already applied. Do not use these coatings on components unless specified. These coatings can affect the final torque, which may affect the operation of the component. Use the correct torque specification when installing components in order to avoid damage.

2. Install the ECT sensor.

NOTE: Refer to Fastener Notice in Service Precautions.

Tighten the ECT sensor to 25 N.M (18 lb ft).

3. Connect the ECT sensor electrical connector.
4. Fill the cooling system. Refer to Draining and Filling Cooling System (LS4 Static Fill) Draining and Filling Cooling System (L26, L32 Static Fill) Draining and Filling Cooling System (GE 47716 Fill) in Cooling System. See: Engine, Cooling and ExhaustCooling SystemService and Repair

Turns out the 2006 Grand Prix (at least with the 3800) required the removal of part of the exhaust to even get to the sensor.

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

Could be the computer controlled of the relay-also try replacing the engine thermostat and see what happens it controls the engine temperature sensor.

Try swapping it with a like one and see what happens-don't work double check wiring at the CTS, Fan relay-if okay could be the computer control circuit of the relay-

There is a sensor right by the thermostat. But there may be 2 1 for the computer and the other for the fan. I't s a simple disconnect the wiring harness and unscrew it and put another in.

Yes you can do it-look below its for a 3.8 liter engine.

That is it. You are over-thinking it. Relax.

It's on the top left rear of the engine below the throttl body.