Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

2009 Hummer H3 AlphaFACTORY OEM SERVICE PROCEDURE

Removal Procedure

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

Fig 1: Engine Coolant Temperature Sensor Replacement

Courtesy of GENERAL MOTORS CORP.

Drain the cooling system below the level of the ECT sensor. Refer to Cooling System Draining and Filling (Static Fill) or Cooling System Draining and Filling (Vac-N-Fill) .
Disconnect the engine wiring harness electrical connector (1) from the engine coolant temperature (ECT) sensor.

Fig 2: ECT sensor

Courtesy of GENERAL MOTORS CORP.

Remove the ECT sensor (1).

Factory Service Tools

Use the Manual With the Right Hardware

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.