Ever since I got 'rear-ended'....
 

It happened in on a slick patch of black ice in the winter of 2013...after I slide (into a curb as I was braking for a red light) I could see that the car coming up behind me was not going to stop either. The impact was probably only a few mph--its hard for me to say--neither my passenger nor I were injured just shook up. There was no visible damage to the rear bumper but ever since that fateful Sunday morning my gas gauge has been messed up. Most of the time the needle goes past the 'full' mark and interferes with the temperature gauge needle. Rarely does it operate properly. A retired GM engineer suggested it could be a loose ground cable. I just paid 5 bills to replace an O2 sensor (needed to pass air quality test and hence obtain new plate stickers) so I am looking for a less expensive solution to this problem. (Today after adding five gallons of gas to the tank the needle went lower--but still past the 'full' mark--which has got me looking for some answers anew.) Is this a float problem? Is it serviceable/probable in the driveway? Thanks for any input.