HELP with diagnostic codes

Discussion in 'GM Powertrain' started by vinceseg, Jun 2, 2012.

  1. vinceseg

    vinceseg New Member

    I've been experiencing a bit of rough idle since I've owned my 05 Tahoe (01/12) and then it seems to smooth out. Until this week, and now it stays very rough at idle almost like it's ready to stall and the check engine light came on today.

    Got 3 codes...

    P0300 - Multiple misfire detected
    P0174 - Bank 2 System too lean
    P0151 - O2 sensor low voltage Bank2 Sensor1

    Do you think this is as simple as the O2 sensor or is that getting thrown because of a different issue?


    Last edited: Jun 2, 2012

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor is information, regarding each of the Trouble Codes you've posted above, hopefully the infor. will be able to give you some help with each Code,

    A Code P0300..........Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.
    A P0300 code indicates a random or Multiple Misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why,

    .....Code P0300.....may mean that one or more of the following has happened:

    • Faulty spark plugs or wires
    • Faulty coil (pack)
    • Faulty oxygen sensor(s)
    • Faulty fuel injector(s)
    • Burned exhaust valve
    • Faulty catalytic converter(s)
    • Stuck/blocked EGR valve / passages
    • Faulty camshaft position sensor
    • Defective computer

    A Code P0174....Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is generally the side of the engine that doesn't have cylinder #1.

    .........P0174.....may mean that one or more of the following has happened:
    • The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
    • There could be a vacuum leak downstream of the MAF sensor.

    .....A Code P0151.....refers to the first oxygen sensor on Bank 2 . P0151 means the O2 oxygen sensor's voltage remained low for longer than 2 minutes. This, is interpreted by the ECM as a low voltage condition and sets the MIL. Bank 2 Sensor 1 is located in front of the catalytic converter

    Code P0151.....may mean that one or more of the following has happened:

    • Faulty O2 oxygen sensor
    • Short to voltage on O2 signal circuit
    • High resistance or open on O2 signal circuit
  3. vinceseg

    vinceseg New Member

    TYVM Mike. Wow it doesn't exactly narrow it down huh? I have a mechanic friend that seems to think it can be a leaking intake manifold gasket which says is common on the 5.3 and could cause the lean condition. I'm going to have him look at it, not the stealership they've been getting way too much of my money lately. I just hope it isn't the catalytic.

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    I would look at finding/locating the Random Misfire First, and then check the 02 Sensor on Bank 2 Sensor 1, which the 02 Sensor Located on the Passenger side of the Engine, in Front of the Catalytic Converter.
  5. vinceseg

    vinceseg New Member

    Probably a stupid question but how do you check an O2 sensor? Do you bypass it somehow and see if it corrects the rough idle?

    I also assume I shouldn't really be driving it in this condition? Is 20 miles or so to get to my guy to diagnose it ok? Thanks.
    Last edited: Jun 2, 2012
  6. vinceseg

    vinceseg New Member

    Was the O2 sensor.
  7. dpeter

    dpeter Epic Member 5+ Years 500 Posts

    All that from an O2-sensor? Thanks for posting back with the resolution.
  8. vinceseg

    vinceseg New Member

    Mechanic says it would normally also throw P0171 if it was the intake, which is too lean on the drivers side. I managed to get both replaced. ;)

Share This Page

Newest Gallery Photos