Coolant sensor location

Hi,

It's on the rear of the cylinder head. See picture 1.

Here is a link that explains how to replace one:

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Here are the directions specific to your vehicle. The remaining pics correlate with the directions.

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2008 Cadillac STS RWD V8-4.6L
Engine Coolant Temperature Sensor Replacement
Vehicle Powertrain Management Sensors and Switches - Powertrain Management Sensors and Switches - Computers and Control Systems Coolant Temperature Sensor/Switch (For Computer) Service and Repair Removal and Replacement Engine Coolant Temperature Sensor Replacement
ENGINE COOLANT TEMPERATURE SENSOR REPLACEMENT
Engine Coolant Temperature Sensor Replacement

Removal Procedure

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

pic 2

1. Turn OFF the ignition
2. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement (See: Fuel Injector > Removal and Replacement) .
3. Drain the coolant to below the level of the engine coolant temperature (ECT) sensor. Refer to Cooling System Draining and Filling (Static Fill) (See: Cooling System > Removal and Replacement)Cooling System Draining and Filling (GE 47716) (See: Cooling System > Removal and Replacement) .
4. Disconnect the ECT sensor harness connector.

pic 3

5. Remove the ECT sensor.

Installation Procedure

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

Notice: 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.

pic 4

1. Coat the sensor threads with sealer GM P/N 1050805, or equivalent.

Notice: Refer to Fastener Notice .

2. Install the ECT sensor.

Tighten the ECT sensor to 20 N.m (15 lb ft).

pic 5

3. Connect the ECT sensor harness connector.
4. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement (See: Fuel Injector > Removal and Replacement) .
5. Refill the coolant system. Refer to Cooling System Draining and Filling (Static Fill) (See: Cooling System > Removal and Replacement)Cooling System Draining and Filling (GE 47716) (See: Cooling System > Removal and Replacement) .

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Let me know if this helps.

Take care,
Joe

You are very welcome. Let me know if you need additional help or just have questions.

Take care,
Joe