What component causes a p0171 system too lean bank one error code?

Answer 1

Addition to previous answer:Seriously - before you go replacing anything, check and clean your EGR valve first. If this doesn't clear up your problem, then check the MAP or MAF sensors, o2 sensors, whatever. Had weird symptoms for weeks or even months. Surging, delayed acceleration, rough idle, stalling, and a general feeling of misfire when accelerating. Had a trouble code of P0171 only. Replaced fuel filter, MAP sensor, and low and behold it was a dirty EGR valve. Nice $4.00 can of carb cleaner fixed it. Answeroxygen sensor, vacuum leak, and yes it could most definitly be if you swaped the wires of the firing order accidently you will get a code p0171 so double check Mine was a vacuum leak. I have a 2002 Sport Trac with just over 112,000 miles, I had a vacuum leak at the throttle body, which was part of an assembly Ford dealer sells. They dont sell just the rubber elbow I needed, so I optioned to get the assembly and replace the PVC while I had it apart. The vacuum leak at the throttle body was giving me DTC of P0171 and P0174. After I had gone through cleaning the MAF sensor, cleaning the combustion chamber, throttle body, and fuel injectors with a professional fuel system cleaning kit from Berryman Chemtool. I found the vacuum leak. I have replace the vent tube and PVC valve. I reset my computer and I don't have any codes.

I think you mean PCV, not PVC. I had the same 2 codes on my 1997 F-250 7.5l. Ford replaced the PCV and vacuum line that connects to it.

I had the code P0171 on a Ford Contour 1998 2.0L GL. I replaced the PCV hose.

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On my 1998 Ford F150 i replaced the fuel filter, air filter and i cleaned the MAF (Mass

Air Flow Sensor) with a can of Mass Air Flow Sensor Cleaner. I then disconnected the NEG battery cable for about 30 minutes to reset the error code. That fixed the problem for me.

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I have a 1998 F150 5.4 - the failure on mine was a vacuum leak at the throttle body end of the pcv line.