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Communities > Diagnostics > USA Cars > help codes p0171 and p0174
help codes p0171 and p0174

1208 Views 6 Replies Latest reply: 2022-03-20 23:33:08


  •   Level 1   
    (5) points

    2021-05-25 21:49:39
    I have a GMC Yukon 2005 engine 5.3 long fuel trim goes up to 25% with new O2 sensors 4 are new also new maf , No vacuum leaks ,new fuel pump, filter ,regulator also new ,service to fuel injectors all are working fine, new intake manifold gasket , water test and ignition fluid test pass both and still having code P0171 and P0174 system to lean what else can be ?

    Tags: p0171 , and , p0174

    Reply

  •   Level 6   
    (475) points
    RLAFFECT

    2021-05-26 23:00:18 (Reply to:)

     check the purge valve if stuck open
    Reply

  •   Level 2   
    (45) points

    2021-06-30 12:35:58 (Reply to:)

     Also check your (VLOM) valve lifter oil manifold solenoid to be sure it is working.
    Reply

  •   Level 1   
    (9) points
    DwayneMcCaslin

    2021-08-01 16:13:11

    E 85 fuel
    Reply

  •   Level 7   
    (1473) points
    Kevin H

    2021-08-05 21:06:52 (Reply to:)

    What is the fuel pressure? What does the freeze frame data read? Did you clean the
    MAF sensor?
    Reply

  •   Level 1   
    (3) points

    2022-03-19 23:19:30 (Reply to:)

    Did you figure out what is wrong?
    I have same problem in three different cars
    Reply

  •   Level 5   
    (342) points
    witsend

    2022-03-20 23:33:08 (Reply to:)

     Brake booster, PCV, low compression, cylinder misfiring, un metered airflow, stuck open canister purge valve?
    Reply
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