So my 2003 Cavalier LS is still giving me trouble, so today I went out and bought a 2004 LS Sport, and on the way home from the dealer it threw 2 codes and started idling high. I noticed the gas gauge handle slowly increase as I drove home and then it started moving in a more jerky pattern, up and down. Right as I noticed this a red indicator came on the cluster so I pulled into a gas station, assuming this to be a low fuel level indicator and a broken fuel gauge, but while filling the tank I read the manual and found this to be low coolant, so I filled the reservoir. The next weird thing was that the gas nozzle cut off late when fueling causing about a cup of gas to spill on the ground. Then I cranked it back up and the indicator light did not come on, so I thought I was good to drive, but it immediately started idling high, smooth, but high, about 950~1000ish rpm when stopped, which is typically the range this car idles at when there is a problem, regularly it idles at about 550. Then the check engine light came on, so I went straight home, I was taking it to get it registered, but that will wait.

When I got home I checked the codes and they are P0134 O2 Sensor Circuit No Acctivity Detected Bank 1 Sensor 1 and the other code is P0171 System Too Lean Bank 1. Now I figure it is a bad upstream O2 sensor, but because the fuel gauge is not working and the tank overflowed, I am wondering if this could be a bad vapor canister, purge valve, fuel pump, or bad fuel pressure sensor. Has anyone encountered something similar to this? I figure it best not to drive it until it is fixed, funny now I have 2 Cavalier LSs that can not be driven.