Hi, I’m having some problems with my 2002 Chevy Impala. It was having an engine code of Fuel Lean Bank 1 and was hard to start with bad gas mileage which the car mechanics thought was just a broken fuel line end. Then a few days after that was fixed the gas mileage started getting bad again (or it might have stayed bad but didn’t pay close enough attention to it at first) and the P0171 code is on. The mechanics wrote “found lean due to failed oxygen sensor”. I didn’t get it fixed because of how much they were going to charge. But now it is incredibly hard to start again! What on earth is going on?
If P0171 is the only code you have, it is not likely a bad O2 sensor. That would most likely set its own code as well as P0171. Check for cracks in the intake system between the engine and the mass airflow sensor as well as vacuum leaks in lines and the intake manifold
From your post I see 2 problems; 1) your mechanics aren’t very good and 2) you don’t want to pay to make the repairs.
Both of these conditions will cause your car to continue to run poorly. I’d suggest you find a better mechanic and pay them for the diagnosis time and to repair your car if you want to continue to drive it.