Rattling noise from under the hood

KYfinfan, I am sorry to hear you are having this concern. I would like to look into this further for you. Can you please email us at socialmedia@gm..com with more information? I look forward to hearing from you soon. Erica Tiffany GM Customer Care

Just an FYI for someone that may be having the same issue. It was the front catalytic convertor. The way it was made was different from most vehicles so the part cost $500+. There was no way to bypass it and put on a universal convertor($125). Apparently this is a more common issue with the G6 than it should be. Consider this before buying one. A $200 repair for most cost me $700.

I have a Pontiac g6 2006 and I experienced a similar rattling noise. Mine was the dust cover on on the exhaust under the engine. The o ring holding it on became loose. I just took the whole thing off.. the dust cover.. and have never had problems or rattling after that. Hope that is your issue.

Recently bought 05 G6. After few weeks, notice rattles from engine compartment.One was loose heat shield. Removed for now. Upon starting, all is quiet. After couple minutes rattling begins, sounds almost like cavitation. Put screwdriver to exhaust and ear. Seems definitly coming from upper exhaust. WHY? Only at idle, quits when under power.