Exhaust Buzz Noise 2000 - 2200 RPM - 05 Cadillac STS - kw load LH2 3.6 4.6 LY7 moan rear resonance vibration

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

2005 MY Cadillac STSs with an LY7 V6 built prior to June 25, 2004 or an LH2 V8 built prior to August 2, 2004, may exhibit a buzz type noise that can be heard from inside the vehicle during driving conditions when the engine is between 2000 and 2200 RPM. The noise is most noticeable when the vehicle is under a slight load at the above noted RPMs for an extended period of time.

The noise may be caused by the exhaust Resonator heat shield. Remove the exhaust resonator shield and install a rear tunnel insulator P/N 15218128. The push-pin fasteners come with the insulator.

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Please follow this diagnosis 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. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(05 Cadillac STS)

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