this is indicating that bank 1 is going lean, meaning that either one side of an engine (v6 or v8) is going lean or in the case of a I4 the whole engine. many reasons could be associated with this and it is impossible to answer without much more information that a shop could provide for you.
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: Fuel System 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)
Trouble code P0171 means: Fuel System Too Lean - Bank 1