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.
2008 Hummer H3 L5-3.7LFACTORY OEM SERVICE PROCEDURE
Knock Sensor: Service and Repair
Knock Sensor Replacement
Removal Procedure
1. Raise and support the vehicle only high enough to access the knock sensor through the wheelhouse. Refer toLifting and Jacking the Vehicle (Service and Repair) .
2. Remove the left wheelhouse liner. Refer to Wheelhouse Panel Replacement (Front) (Service and Repair)Wheelhouse Panel Replacement (Rear) (Service and Repair) .
3. Disconnect the engine wiring harness electrical connector (3) from the knock sensor (1).
4. Remove the knock sensor bolt.
5. Remove the knock sensor (1).
Installation Procedure
Notice: Refer to Fastener Notice (Fastener Notice) .
1. Install the knock sensor (1) and the bolt to the engine block, positioning the electrical terminals rearward.
Tighten the bolt to 25 N.m (18 lb ft).
2. Connect the engine wiring harness electrical connector (3) to the knock sensor (1).
3. Install the left wheelhouse liner. Refer to Wheelhouse Panel Replacement (Front) (Service and Repair)Wheelhouse Panel Replacement (Rear) (Service and Repair) .
4. Lower the vehicle.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.
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