1999 Chevrolet Silverado 1500 Logo
Posted on Mar 05, 2011
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My truck is showing codes 171 and 174. Can you help

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  • Posted on Feb 15, 2013
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If car starts drive and when codes appear get tune up

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  • Posted on Mar 05, 2011
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P0174 Generic Definition

Fuel Trim Bank Two Condition
- The ECM has detected a rich or lean air/fuel ratio condition on engine bank two

Probable Cause[s]

  1. If bank one and two are set together suspect a fuel pressure condition or MAF sensor fault
  2. Failed HO2S21
  3. Ignition misfire condition
  4. Fuel injector problem
  5. Engine mechanical condition




    P0171 Generic Definition

    Fuel trim bank one condition
    - The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.

    Probable Cause[s]

    1. If bank one and two codes set together suspect fuel pressure or MAF (Mass Air Flow) Sensor
    2. Oxygen sensor defective
    3. Ignition misfire-repair
    4. Fuel injector problem












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      5 Related Answers

      kelly

      • 121 Answers
      • Posted on Mar 09, 2010

      SOURCE: trouble codes 171, 174, 137 & 401 came on after engine replacemen

      did they ever reflash the ecm with the new codes for the motor

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      Marauder325

      • 145 Answers
      • Posted on Nov 03, 2009

      SOURCE: check engine light on computer codes 171 174

      switch, we run off snitches. 171 174 banks 1 & 2 Lean. Most likely cause are Upper Intake Manifold Gaskets, failed seals. It's not 1990 on. It's 1996 and on OBD2.

      Anonymous

      • 199 Answers
      • Posted on Jan 05, 2009

      SOURCE: codes #171 & 174

      first check out for o2 sensor if its faulty this can show up.but if its proper.Evaporative emission control system leak very small 171 System too lean (bank 1) 174 System too lean (bank 2) 

      Anonymous

      • 55 Answers
      • Posted on May 24, 2010

      SOURCE: 200 lincoln ls 3.9 codes 171 174 300

      171 and 174 mean it is running lean and 300 means a random cylinder misfire

      duane_wong

      Duane Wong

      • 6826 Answers
      • Posted on Jul 08, 2010

      SOURCE: Codes 171 174 2002 gmc sierra 5.3

      Try some injector cleaner in order to see if the lean condition improves. Lean conditions can sometimes be caused by o2 sensors or other sensors that are not within specifications.

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      On my 2002 yukon 1500 I have trouble codes of 171,174, 420 what is my problem

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      Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.
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      Keep getting ses codes p507 p171 p174

      The codes you show are all about air leaks. The 507 is about the IAC and may simply be the system noting the connection was unplugged.

      The 171,174 are lean codes and usually mean more air is coming in than is needed. Did you use a water mist to check for leaks? Have you checked Vacuum solenoids for leaks?, the EGR diaphram?

      You did not indicate the engine and vehicle this problem was on. Some of the 6 cylinder products had sandwich type manifolds and the upper and lower chambers had a gasket which would dissolve and leak internally.

      Some people have had problems with the runners on dual plane manifolds, but I question whether a 171, or 174 could generate from this defect.

      I think you should retest with a water spray after clearing the computer.
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      I have a 91 Buick century 3.3l that is reading out check engine codes 12,26,27,44. I can't find a chart anywhere that tells me what the codes mean. Can you help me out? Thanks, Joe

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      Check engine light is on,codes 171,174,system lean,codes came back as 2 oxygen sensor's before cat/conv,do they need to be replaced or could it be something else causing it, any help would be great!!!

      O2 SENSORS ARE BAD MOST LIKELY I WOULD CHANGE THEM DISCONNECT THE BATTERY FOR 5 MIN. ( IF YOU DONT HAVE A SCANNER) THIS WILL RESET YOUR COMPUTER AND SHOULD MAKE THE SERVICE ENGINE LIGHT GO OUT.
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