Z28 is running normal, just filled up an got 22MPG, when I went to Autozone the guy said it trip twice. He also said I might need a gas cap or I filled up with gas without shutting down. I never do that. I did get this tank of 92 Octane from BPAmaco at another station then usual.

Any ideas what caused this or what it is. Autozone reset the codes and it is clear so far BUT the last SES I got did that for awhile till it came back

 

That P0442 code you have is an EVAP/ GAS code.. one of the most common reasons for throwing this code that you gas cap is not tightened, so check that, clear the code, and see if it comes back. If it does you might have a leak in the evap system which any dealer can diagnose w/ there evap smoke machine.

Good Luck