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For 1990-2009 cars only

High Knock Retard Inspect For Knock Sensor Wire Chafe - keywords 4.8 5.3 6.0 6.2 chafe detonation DTC knock L76 L92 LC9 LH6 LMG LY2 LY5 LY6 MIL P0326 P0328 P0333 sensor SES wire wiring

Subject:High Knock Retard Inspect for Knock Sensor Wire Chafe

Models:2007-2008 Cadillac Escalade
2007-2008 Chevrolet Avalanche, Express, Silverado, Suburban, Tahoe
2007-2008 GMC Savana, Sierra, Yukon



This PI was superseded to update DTCs that may occur with this type of wire chafe. Please discard PIP4229.


The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

The customer concern may be a lack of power and a ses light on.

During diagnosis a technician may or may not find DTC P0326 P0328 or P0333.

When accelerating and low power is noticed, the knock retard may be seen as high as 15 degrees.

Recommendation/Instructions:

Complete the current SI diagnostics for any trouble code or symptom found. If DTCs P0326 P0328 P0333 are found, and low power has been verified, inspect for a wire harness chafing concern.

The wiring harness located on the left side of the engine may contact the front differential mounting bracket. Repair and reposition the wiring harness as needed. Evaluate the repairs and verify the knock retard readings are not excessive.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.