Before you go and buy the O2 sensor, like everybody does, get a hose of a least to feet in length, put it against your ear, and the other end, towards the engine, start listening for a hissing sound from the engine, which means there is a vacuum leak, either, from the gasket in your intake manifold, or somewhere on the side of your engine where cylinder one is located., Since the code is related to that side of your engine.
Check all vacuum hoses for cracks and make sure they are secured in place.
Low fuel pressure or a restricted fuel filter can also cause that code to pop up. Have the fuel pressure and flow checked also.
burn the car
2000 ford lightning. P1540,po171.po174
code po171
Too lean bank one check fuel pressure-your pump is probably going out.
Trouble code P0171 means:System too lean (bank 1)
Code P0171 means System to lean (bank 1)
Trouble code P0171 Means: System too lean (bank 1)
first try cleaning your mass air flow sensor.
po171--- system to lean (bank # 1)
PO171 = system adaptive fuel too lean (bank 1) PO174 = system adaptive fuel too lean (bank 2)
P0171 System too Lean (Bank 1)
Not much info to go on but you could have a large vacuum leak in bank one.