Pontiac problems? Ask a mechanic for answers ASAP
Welcome to Just Answer I'm Chris aka Moose, I'm sorry you are having problems with your G6 EGR. I will do my best to help you get this resolved. If I happen to be helping another or step away during our communication, please know I will follow up as soon as I am back available/online.
IF the EGR is sticking open this will dump excessive EGR into the intake making the air-fuel ratio incorrect. That will reduce engine performance resulting in more fuel usage. Here is a link showing all the steps that can be done for diagnosing and addressing a 0401 code https://www.dropbox.com/s/vx3osau4fzff8ey/EGR0401G6.png?dl=0
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It can be an exhaust restriction causing excessive EGR flow from to much back pressure.
You are welcome