What causes a PO826c code and is it hard and expensive to fix? on 2005 Chevrolet Malibu Maxx

Model LS 3.5 engine. I got this code along with PO449b & PO455b. I had a very bad and loose gas cap and have just recently replace it with an OEM cap from the dealer. Once I got the new cap the shop reset my engine light and said to see if it stayed off but as soon as I filled up and restarted it came back on. Why would a low range up/down shift switch affect my inspection status in the first place? I almost never take it out of drive.

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1 answer 5 comments
i show no po828 plaes recheck that the other codes are evap codes and can cause you fits have them diag and get an est and save time and $
It was a PO826c, not PO828. Thank you for the fast response.
sorry no glasses po828 has to do with the tap shifter circuit in the car
a big $ fix?
not really if you break it down. depends on the diag if its parts or circuits. but u can fix in stages misfire 1st
Thanks for your help. Greatly appreciated.
Ed