When I first bought this 2006 Monte Carlo it was reading just above 3/4 of a tank when I filled it up. I dropped the tank and found that the sending unit was reading 40 ohms on empty and 200 ohms on full. It was supposed to be reading 40-250 ohms. Cleaned the wiper area with a nylon brush and citrus cleaner which corrected the problem. Also there is a short length of wire connecting the tank sender to the chassis.