scanner code 0171 system too lean bank 1

I think that it has something to do with your fuel system not being able to fully correct an issue with fuel trimming, rich or lean,, something has happened which is preventing the pcm from setting the optimum parameters... any work done lately on the engine compartment,, I would check all the air cleaner parts,, make sure all vacuum hoses are hooked up and in good shape, no little rips hiding underneath,, check pcv system and fuel lines, make sure all in good condition.. if nothing is obvious, you may have to take it to a reliable repair shop or the dealer,,, tracking it down requires some specialized equipment, unfortunately... good luck