fyrebryan

Post Catalyst Fuel Trim System High Limit Bank 1

Any ideas how to trouble shoot this code? I was originally thinking that it might just be a bad O2 sensor, but I'm not sure and wanted to ask here before I went out and bought a new sensor.

Wife has been driving the car and she's mentioned that the exhaust smells strange and it's been smoking some, however when I've driven it, it only seems to smoke when it is cranked, not during normal driving. She also noted that sometimes when going down a hill, if she takes her foot off the gas and coasts down the hill, the hhr will backfire.

This is on a 2008 HHR SS M5 100% stock, no stage kit or tunes, or any other mods.

Can anyone help?

Edit: also thought it might be possible there was some bad gas. not 100% sure though. would buying a bottle of fuel system cleaner or octane booster help any?