I'm having the same issue on a 2005 Malibu 3.5, check engine light is on and it gives a message to check gas cap. We have replaced the cap, no change. It shows a PO449 code on the scanner. Would it have the same tcm-batt fuse under the hood? I've posted on a Malibu board, but haven't received any response.

 

PO449 - Google Search

check and make sure the electrical connector is still connected and not broken. I had one rip in half on a j-body.

 

Thanks for the reply, it helped a lot. Finished the repair just now, $25.00 in parts and about 2 hrs work. The solenoid could not be more of a pain to get to, but I guess that's the way it goes with newer cars.....