Trouble code P0171 means: Fuel System Too Lean (Cylinder Bank 1)
http://www.aa1car.com/library/ford_lean_codes.htm
P0171-system too lean bank 1 and P0174-system too lean bank 2
p0171 andpo174 mean that you're car is running lean
It means your vehicle is running lean you will need to replace the intake manifold gasket, as it is plastic and the seal wears out.
Trouble code P0171 means:System too lean (Bank 1)
Trouble code P0171 means: System too lean (Bank 1)
Trouble code P0171 means:System too lean (Bank 1)
Trouble code P0171 means:System too lean (Bank 1)
Trouble code P0171 means: System Too Lean (Bank 1)
Trouble code P0171 means: Bank 1 Combustion Too Lean
Trouble code P0171 means:System too lean (Bank 1)
Trouble code P0171 means:System too lean (Bank 1)