I have a P0171 code (lean bank 1 sensor 1) on my 2002 toyota camry 4 cylinder. I don’t have any other codes except for an unrelated P1780 neutral safety switch code. It has had both codes for over a year.
I have replaced the fuel filter, the upstream o2 sensor, and the PCV valve. I also cleaned the MAF sensor. The mechanic performed a smoke test and found no vacuum leaks. Did a fuel pressure test and it’s normal. Mechanic thought it would be fuel pressure because the car starts a bit slow when cold, but nope. The car runs great and still gets great gas mileage. I’ve never experienced a misfire in my 12 years of owning the car. I am asking because I am at a loss as to what it could be. Thanks.