P0171 - My experience and thank you

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by ron57108, Jul 10, 2021.

  1. ron57108

    ron57108 Junior Member

    Jul 4, 2011
    2011 Prius
    First of all - thank you to everyone who commented on the P0171 threads throughout this forum!
    I would love to go back and "like" each suggesting I ran across. But, they are way too numerous to even begin to accomplish that.
    I do want to circle back here and, hopefully, help anyone encountering this error for the first time.
    - 2011
    - 140k miles
    - always serviced appropriately
    - the only "out of ordinary" things I've ever done to the car is a front wheel bearing and an accessory battery.

    Somewhere about 140k, the check engine light appeared. Everything seemed to be running ok. I had noticed a reduction in fuel economy over the years, but I chalked that up to age. So, I got my phone and obdii adapter out. That's when I found the P0171.

    I tried every "easy" thing I could find in these forums:
    - replace PCV (just cause it is easy and cheap)
    - cleaned MAF as best I could without total disassembly
    - checked all hoses
    - replaced spark plugs
    - and on and on
    - really, about the only thing I didn't do was replace the O2s and take apart/clean the manifold

    So, left with (seemingly) no other option, I was able to find a fuel pump from a wrecked 2012 with 60k on ebay. The fuel pump on the 2011s vs 2012s had a very similar but not identical fuel pump assembly. My 2011 had a part number of 7702047080 and the 2012 had a 7702047081 part number.
    That did it!
    After clearing the code and driving a few 100 miles, even the "permanent" P0171 went away.

    A note on the fuel pump part numbers. The 7702047081 assembly is a direct replacement for my previous 7702047080 assembly. That is NOT true for the components attached to the assembly. The 2012 assembly I bought came damaged (looked like they just chopped it out of the previous car). So, I had to move the components from the new assembly housing to my old assembly. That was super easy, but I noticed that the pump itself has a different electrical connection and the fuel level potentiometer was slightly different. SO, if you are looking for a new fuel pump be careful about buying just the pump separate from the entire assembly.

    So, thanks again everyone.