If you are not able to login to the forum, please Contact Us here to let us know. Thanks!

Support FSC and see no ads! - Click Here
Page 1 of 2 12 LastLast
Results 1 to 20 of 25

codes p0171 and p0174

This is a discussion on codes p0171 and p0174 within the Technical / Maintenance forums, part of the General Discussion category; 99 Chevy Silverado EXT Cab Short bed with 5.3 My SES light came on about a month ago with code ...

  1. #1
    Registered User
    Join Date
    Jun 2008
    Location
    Central Indiana
    Posts
    7

    codes p0171 and p0174


    Support FSC and see no ads! - Click Here
    99 Chevy Silverado EXT Cab Short bed with 5.3
    My SES light came on about a month ago with code p0171 and p0174. and has been on and off as the temperture changes, on more when cold outside. Last night it was @ 3 degrees, SES was on, the engine idled @ 800 rmp's then drop to 500 and back up to 800 over and over. When the engine was cold and after it warmed up.
    It runs fine otherwise, with the exception of a drop in gas milage last fillup form 17 to 11 MPG. I have sprayed cab & injector cleaner around the upper in take and notice no change in engine sound. I don't think it is the fuel pump because it runs ok on the highway. I don't think it is the O2 sensor, I'm not sure about the MAF sensor and how to check it?

    Any ideas?
    Thanks

  2. #2
    Homesick NBer
    Join Date
    Jul 2005
    Location
    Edmonton, AB (but still an easterner at heart)
    Age
    29
    Posts
    2,395

    Re: codes p0171 and p0174

    DTC P0174 Fuel Trim System Lean Bank 2
    Circuit Description
    In order to provide the best possible combination of driveability, fuel economy, and emission control, the vehicle uses a closed loop fuel metering system. While in closed loop, the VCM monitors the oxygen sensor signal voltage. The VCM adjusts the fuel delivery based on a signal voltage.The long and short term fuel values, which a scan tool can monitor, indicates a change made to the fuel delivery. Ideal fuel trim values are around 0% (128 counts); if the oxygen sensor signal indicates a lean condition, the VCM adds fuel. This results in fuel trim values above 0%. If the oxygen sensor detects a rich condition, the fuel trim values will read below 0%. This indicates that the VCM is reducing the amount of fuel delivered. The VCM sets this DTC when an excessively lean condition is detected.

    Conditions for Running the DTC
    • No active O2 sensor DTCs

    • No active TP sensor DTCs

    • No active MAP sensor DTCs

    • No active EGR DTCs

    • No active EVAP system DTCs

    • No active ECT sensor DTCs

    • No active MAF sensor DTCs

    • No active IAT sensor DTCs

    • No active VS sensor DTCs

    • No active misfire DTCs

    • Throttle position less than 70%

    • Engine speed is between 575 and 4,000 RPM

    • The BARO greater than 70 kPa

    • The ECT is between 75 and 114C (167-237F)

    • The MAP is between 22 and 85 kPa.

    • The IAT is between -8 and 76C (46-169F)

    • The MAF is between 3 and 85 g/s

    • The vehicle speed less than 85 MPH

    Conditions for Setting the DTC
    The average of the short term fuel trim values over a period of 120 seconds indicates that a lean condition is present.

    Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.

    • The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records.

    Conditions for Clearing the MIL or DTC
    • The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.

    • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22C (40F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70C (158F) during the same ignition cycle.

    • Use a scan tool in order to clear the DTCs.

    DTC P0171 Fuel Trim System Lean Bank 1
    Circuit Description
    In order to provide the best possible combination of driveability, fuel economy, and emission control, the vehicle uses a closed loop fuel metering system. While in closed loop, the VCM monitors the oxygen sensor signal voltage. The VCM adjusts the fuel delivery based on the signal voltage. The long and short term fuel values, which a scan tool can monitor, indicate a change made to the fuel delivery. Ideal fuel trim values are around 0% (128 counts). If the oxygen sensor signal indicates a lean condition, the VCM adds fuel. This results in fuel trim values above 0%. If the oxygen sensor detects a rich condition, the fuel trim values will read below 0%. This indicates that the VCM is reducing the amount of fuel delivered. The VCM sets this DTC when an excessively lean condition is detected.

    Conditions for Running the DTC
    • No active O2 sensor DTCs

    • No active TP sensor DTCs

    • No active MAP sensor DTCs

    • No active EGR sensor DTCs

    • No active EVAP system sensor DTCs

    • No active ECT sensor DTCs

    • No active MAF sensor DTCs

    • No active IAT sensor DTCs

    • No active VS sensor DTCs

    • No System Voltage DTCs

    • No active misfire DTCs

    • Throttle position less than 70%

    • Engine speed is between 575 and 4,000 RPM

    • The BARO greater than 70 kPa

    • The ECT is between 75 and 114C (167-237F)

    • The MAP is between 22 and 85 kPa.

    • The IAT is between -8 and 76C (46-169F)

    • The MAF is between 3 and 85 g/s

    • The vehicle speed less than 85 MPH

    Conditions for Setting the DTC
    The average of the short term fuel trim values over a period of 120 seconds indicates that a lean condition is present.

    Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.

    • The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records.

    Conditions for Clearing the MIL or DTC
    • The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.

    • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22C (40F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70C (158F) during the same ignition cycle.

    • Use a scan tool in order to clear the DTCs.

    i work at a dealer and you will need to take it in and have it hooked up to a tech 2 scanner and have it checked out.

    the test procedure is pretty complicated

    you have to monitor the system in closed loop, and go through, and shut it off and run it through normal. its best to get it diagnosed properly, cause there are way to many things that could cause this, so don't just throw money at it replaceing anything involed in hopes to fix it.
    2003 Chev Silverado 4x4 4.10 gears and it has a 4.8L
    1997 GMC Sierra 4x4 4.3L 4L60E KOSS CD player,16mpg,3.73 gears z71 skid plates <<<sold

    4th year apprentice at Chev Dealer

  3. #3
    GMC RULZZ NEUMANNZZ's Avatar
    Join Date
    Mar 2005
    Location
    San Diego
    Age
    47
    Posts
    20,577

    Re: codes p0171 and p0174

    If its running lean check the fuel pressure.
    O2 GMC RCSB 4.8L V8 AUTO 3.73's
    rebuilt/beefed up 4L60E(at 43,000miles)
    Matching Ninja 500r


  4. #4
    Registered User Anthoney456's Avatar
    Join Date
    Jun 2008
    Location
    Charleston, SC
    Age
    28
    Posts
    389

    Re: codes p0171 and p0174

    a how many mile are on it and you will prob need intake gaskets comman problem with then most likely leaking on driver side

  5. #5
    Registered User Anthoney456's Avatar
    Join Date
    Jun 2008
    Location
    Charleston, SC
    Age
    28
    Posts
    389

    Re: codes p0171 and p0174

    a how many mile are on it and you will prob need intake gaskets comman problem with then most likely leaking on driver side

  6. #6
    I Drive A Silverado
    Join Date
    Nov 2001
    Location
    Tennessee
    Age
    45
    Posts
    112

    Re: codes p0171 and p0174

    Quote Originally Posted by Anthoney456
    a how many mile are on it and you will prob need intake gaskets comman problem with then most likely leaking on driver side
    How much does that cost to fix?
    Previously owned fullsizes

    89 Silverado (2)
    90 Silverado
    92 Silverado
    92 454SS
    95 Silverado Ext Cab
    96 Silverado

  7. #7
    Registered User Bowtie00's Avatar
    Join Date
    Oct 2008
    Location
    Dallas, TX
    Age
    26
    Posts
    408

    Re: codes p0171 and p0174

    Check your fuel trim levels. 02 sensor voltages. Both with scan tool. You are on the right track though.
    2000 Chevy Silverado 1500 4.3L 5 Speed

  8. #8
    formerly mytrucksbigger VenomHP's Avatar
    Join Date
    Nov 2006
    Location
    League City, TX
    Posts
    159

    Re: codes p0171 and p0174

    make sure all the intake fittings are tight, I was throwing the same codes and then a p0300 popped up later so I checked it out and the intake was a little loose, the light hasnt come on since
    02 ext cab z-71 LT 6" lift, FLT LVL 4 4L60E, flowmasters, intake, power programmer, 4:56 gears, traction bars, 35" tires and atlas II wheels

  9. #9
    I Drive A Silverado
    Join Date
    Nov 2001
    Location
    Tennessee
    Age
    45
    Posts
    112

    Re: codes p0171 and p0174

    I just paid $369 at the Chevy dealership to have my intake gaskets replaced and I threw the same code numbers.
    Previously owned fullsizes

    89 Silverado (2)
    90 Silverado
    92 Silverado
    92 454SS
    95 Silverado Ext Cab
    96 Silverado

  10. #10
    2WD MONSTER 2wdchevywt's Avatar
    Join Date
    Aug 2007
    Location
    Connecticut
    Age
    26
    Posts
    984

    Re: codes p0171 and p0174

    2004 SILVERADO 1500 5.3, 37X13.5 TOYO MT, 18X9 XD MONSTERS, 6K HIDS, CUSTOM TUNE, AFE CAI, 6" RCX, 3" BL, RCX KICKER BRACES, COGNITO PITMAN AND IDLER SUPPORT BRACKETS, COGNITO UCA, COGNITO LIMIT STRAPS, PROCOMP AAL, TRUETRAC, 4.88 GEARS


  11. #11
    Registered User Bowtie00's Avatar
    Join Date
    Oct 2008
    Location
    Dallas, TX
    Age
    26
    Posts
    408

    Re: codes p0171 and p0174

    I replaced 4 intake gaskets yesterday on 5.3L, I would of done 2 today but customer declined repairs.
    I would hurry to replaced them because if you run with a vacuum leak it will kill you catalytic converter and it they are not cheap. It is a easy repair, takes around 40 minutes without power tools.
    Last edited by Bowtie00; 12-24-2008 at 04:30 PM.
    2000 Chevy Silverado 1500 4.3L 5 Speed

  12. #12
    Registered User JaredW's Avatar
    Join Date
    Dec 2006
    Location
    Michigan
    Posts
    101

    Re: codes p0171 and p0174

    Did you ever figure out this problem? I am having the same issue with my 02 6.0 with 102,000 miles

  13. #13
    Registered User
    Join Date
    Jan 2009
    Location
    Enfield Ct
    Age
    42
    Posts
    11

    Re: codes p0171 and p0174

    I've got a decent amount of experience on this code, but on my car. Keeping in mind that the diagnostics and the aids are the same, being a different vehicle may trump what I'm about to say.

    Check your battery connections and cables for corrosion. Pull the bolt out and remove the boots to give the cable itself and crimp a good look over. Found the cables to actually be messing with voltage to the sensors slightly and throwing them off to cause a lean bank issue. Being that you are seeing it on both sides it would seem that the common items of maf might be the cause, since finding the cabling issue....I won't rule that out again w/o looking.

  14. #14
    Registered User screamingckn88's Avatar
    Join Date
    Oct 2008
    Location
    Sacramento, CA
    Age
    25
    Posts
    41

    Re: codes p0171 and p0174

    I would clean (or replace if cleaning doesn't work) the MAF sensor. You're running lean on both banks, which would indicate that the MAF is throwing things off, since you already replaced the intake gaskets and that didn't solve anything. If not, you have a vacuum leak somewhere else or possibly bad o2 sensors.

  15. #15
    Registered User
    Join Date
    Nov 2009
    Location
    Canada
    Posts
    3

    Exclamation Re: codes p0171 and p0174

    I have a 2005 sierra you mean to tell me that GM has not resolved this problem yet with regards to the intake? No wonder they are in trouble. Like my truck but they are not made to last like they say. I have been having one issue after another. I still consider my truck to have low K's at 89000 kilometers .

  16. #16
    Registered User
    Join Date
    Apr 2008
    Location
    Columbus, KS
    Age
    26
    Posts
    499

    Re: codes p0171 and p0174

    What if you've got a bank running rich? I've had my engine light come on lately and my mpg's are down. I had it scanned and was told one of the banks are running rich. What could cause this? How would you fix it?

    ANother ? how do you clean your MAF?

    03 GMC. Z71. 16" helo wheels, Bose, 8" MA audio subs, flowmaster super 44 side exit, T bars cranked. 3.73 gears, posi.

  17. #17
    Registered User
    Join Date
    Sep 2009
    Location
    wisco
    Posts
    51

    Re: codes p0171 and p0174

    to op: i've been having the same probs lately.
    cleaned maf, codes disappeared then came back.
    changed fuel filter went away for a bit, came back.
    today i added heet when i filled up and they went away, we'll see how long it lasts.

    and you clean the maf with maf sensor cleaner, just loosen the clamp on the engine side of the maf, and the 4 screws holding the airbox lid on, and the electric connector. remove the piece, spray through it thoroughly and let it dry before reinstalling.
    -quardt

  18. #18
    Registered User
    Join Date
    Nov 2009
    Location
    Canada
    Posts
    3

    Re: codes p0171 and p0174

    It funny that you say it went away when you added HEET. That is when I noticed the Service Engine light is when I used the Heet,it may have been just by coincidents.Bank two running rich

  19. #19
    Registered User
    Join Date
    Nov 2009
    Location
    Canada
    Posts
    3

    Re: codes p0171 and p0174

    replaced O2sensor on passenger side per cat and all is fine. going on 3 weeks

  20. #20
    Registered User
    Join Date
    Sep 2009
    Location
    wisco
    Posts
    51

    Re: codes p0171 and p0174

    anybody have specs on the voltage or amps a o2 sensors supposed to be reading? my light came back on so i changed the intake gaskets went away for a bit but its back again. i just want it gone. putting on an external inline fuel pump to get pressure up to see if that helps.
    -quardt

 

 
Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •