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Losing power, throwing PO131 and PO151 codes when pulling a trailer.

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by boycbronco, Oct 29, 2011.

  1. boycbronco

    boycbronco New Member

    I had a lot of trouble this week pulling some grades with my 97 1500 Suburban (5.7L). I only had a very small trailer with an ATV on it behind me, not much weight at all. Had some similar problems last spring, pulling my boat. At that time, simply removing the gas cap seemed to solve the problem.
    This time, it would quickly bog down once I hit a grade, and I was only able to continue by shifting down to 2nd and keeping my foot out of the throttle. If I stepped on the gas, it would typically throw PO131 and PO151 codes (O2 circuit low voltage). I would then have to reset the codes before I could continue.
    A little background (I have been posting on some issues with this rig over the last year or so). In the last year, the spark plugs, spark plug wires, cap (twice), rotor, fuel filter (twice), fuel pump, fuel pump wiring harness, gas cap, and all four O2 sensors and both catalytic converters have all been replaced.
    I am still getting almost 65 psi fuel pressure at ON, and about 55 psi at idle. I have blown compressed air through the vent line (tank to charcoal canister) and the air is getting through okay.

    Any ideas on why I might still be having trouble?
  2. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts

    For Trouble Code's.....P0131 and P0151.......may mean that one or more of the following has happened:

    • Faulty 02 oxygen sensor
    • Short to voltage on O2 signal circuit
    • High resistance or open on O2 signal circuit
    Possible Solutions


    • Replace faulty sensor
    • Repair short, open, or high resistance on 02 signal circuit
    As you have just replaced the.....02 Sensor's.....I would take a look at them, loose connection??......what Brand of 02 Sensor's did you go with/install??.
  3. boycbronco

    boycbronco New Member

    Mike, I will take a look at the wires and connections on the sensors to make sure nothing is shorting out. I replaced them all 4 with Bosch sensors. Hope I don't have to do that again, as it cost a small fortune just to do that!
  4. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts

    Sorry to say and with all due Respect....In some cases Going with and Staying with Factory/OEM Parts......is the Best Way to go.....and this is one of those Cases, also what Brand of Spark Plugs did you go with/install??
    Last edited: Mar 13, 2013
  5. boycbronco

    boycbronco New Member

    Great. I'm sure the factory ones will cost twice as much. I looked at all four and no bare wires, no disconnects, nothing to suggest there would be a short. The plugs are AC/Delco.

    Looking real quick on line, I see O2 sensors by AC/Delco, Delphi, Walker, Denso, Standard, SNG, and NTK. I presume you recommend the AC/Delco, any others?
  6. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts

    The 02 Sensor's are not Cheap and that's for sure!!!......Amazon has A/C Delco 02 Sensor's for your 97" Suburban......for a Very Good Price,

    http://www.amazon.com/ACDelco-AFS105-Oxygen-Sensor/dp/B0013FWACW/ref=au_pf_pfg_s?ie=UTF8&Model=C1500 Suburban|425&n=15684181&s=automotive&Make=Chevrolet|47&Year=1997|1997&vehicleType=automotive&newCar=1&carId=005


    Delphi is another one to look at......and on the Plugs you've got the A/C Delco, once again those are the ones you want.
  7. 2COR517

    2COR517 New Member 1000 Posts

    I've sold hundreds of Bosch O2 sensors, never had a compliant. Don't bother to touch the rear sensors till the truck is running correctly. They have zero input on Engine Control.
  8. boycbronco

    boycbronco New Member

    So, do you recommend swapping out the pre-catalyst sensors only, then?
  9. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts

    I would agree with 2COR517 on replacing just the Up-Stream(Pre-Cat) Sensor's only.
  10. boycbronco

    boycbronco New Member

    Thanks for the tips and the link to the Delco sensors at Amazon. I hope it works ... since the other sensors are still only a few months old.

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