Need Help - Code P0171 Poor MPG

Wheelie · 2011-11-06T15:25:33+00:00

Hi to all. First post. Just need to make a quick check with someone more knowledgeable about this before I jump in to start replacing more stuff. 1999 V6 4Runner with 149,000 miles. Bought 3 months ago for 16 yo son. Runs fine hot or cold Tail pipe color normal Gas mileage is poor (about 14 MPG) I understand it should be 17 to 19 MPG Month ago it threw the check engine light (Code P0171 System Too Lean Bank 1) and so I replaced the air/fuel sensor (oxygen sensor) Two weeks later the check engine light came on again. ODB code reader shows same code (P0171) I removed and cleaned the mass flow sensor and two weeks later same code came back Air filter newish and very clean New spark plugs 25,000 miles ago Passed emissions 2,000 miles ago TPS (throttle pos sensor) replaced a year ago No abnormal oil consumption Anyone experienced this or maybe has better insight into this problem? Maybe a fuel injector? Fuel filter?

Thread starter Wheelie
Start date Nov 6, 2011

SKJRunner01

New member

Sep 16, 2013

PO171 Code. DONE IT ALL

Hey guys....

I am in a pickle. I had the PO171 and the PO420. I cleaned the MAF Sensor replaced all vacuum lines that were broken. Ran a air leak test it all passed. Ran the MAF test, pass, 02 sensor, pass. I ran Cataclean, PO420 code is now gone. PO171 is still here. Now the shop is replacing the fuel filter..... Please if anyone knows. What are the specs for the wave length of the front Sensor compared to the rear?

Thank You
:moping: