Need help with Check Engine Light codes (PO171 and PO174)

[ragmorf]

Can anyone define what CEL codes PO171 and PO174 mean for a 2001 Pathfinder? After reading a few of the other postings, I ran down to AutoZone and got the codes read and my CEL reset. But the other postings I read also warned that AutoZone’s diagnosis is wrong more times then it is correct. Any recommended service options on diagnosing these coded to the precise issue?

AutoZone’s Diagnosis:

PO171 - Fuel system for bank 1 is too lean, Oxygen sensor recognized a rich or lean condition on one engine bank only1- Suspect fuel pressure or Mass Air Flow sensor2- Oxygen sensor defective3- Ignition misfire-repair4- Fuel injector problem

PO174 - Fuel system for bank 2 is too lean, rich or lean air/fuel ratio condition engine bank two1- Suspect fuel pressure or Mass Air Flow sensor2- Failed HO2S213- Ignition misfire condition4- Fuel injector problem5- Engine mechanical condition

[Chris92SE]

usually this is a bad MAF.

you can either clean your current one and hope that fixes it, or you can buy a new one.

Do some searching on the Maxima MAF. I had posted info about mine. I had the same code and it was pinging almost all the time. It turned out to be the MAF sensor. I bought a Maxima one and everything has been fine since.