Design flaw in cabin air filtration system leading to health hazard within the vehicle. On two occasions in my first 16 months of ownership, mice have entered the cowl air plenum area and built nests on top of and out of the cabin air filter material. Both times the filter has become saturated with mouse dander, feces and other materials. Eventually these contaminants work their way through the filter and an odor is noticed inside the vehicle. The mice are believed to enter this area through significant unscreened openings at the ends of a plastic cover over the plenum in the windshield wiper area under the hood. I have contacted GM with regard to this design flaw. Their only response was to establish their case number 711507394608. No further action was taken. So far, my dealer has continued to repair the damage and install new cabin filters. No attempt has been made to block or screen the openings. The truck is regularly garaged with two other non-GM vehicles that do not have this problem. Individuals with respiratory conditions should be concerned about the significant plenum design flaw in these GM trucks.

- Sobieski, WI, USA