P0174 Bank 2 Too Lean - after new Cats & FlowMaster installed

Discussion in 'Performance & Fuel' started by SoundZman, Nov 23, 2011.

  1. SoundZman

    SoundZman Rockstar 100 Posts

    I stated getting a Catalysis Efficiency code on Bank 2 earlier this year. So knowing it was going to be costly, I decided to wait until a better time financially. Well, last week I dropped it off at my mechanic and I opted to replaced both Cats since he had the exhaust system dropped, as well as installing a FlowMaster muffler & standard issue chrome tip.

    My shop drove it for about 30 miles to make sure all was good, and all was good, until I picked it up and drove 3 miles to my house where the CEL came on. I quickly pulled my scanner out and pulled about 5 codes ranging from rich condition to misfire all on Bank 1. Brought it back and my mechanic monitored the o2 sensors (with his very expensive looking scan tool) and found Bank 1 was not responding (switching from high to low voltage) as the others were and as it should have been. So he replaced the only that O2 sensor.

    Picked the truck up today and drove it about 35 miles to a friends house, stayed for about 1 hours then left. Got about half a mile down the road when the dreaded CEL came on again. Pulled the above code P0174 System Too Lean (Bank 2) & 2 - P0101 Mass or Volume Air Flow Circuit Range/Performance.
    Note on the P0101 - this code has pretty much come up with every other code in the last 6 months, so I'm not surprised at all to see it. It also has not trigger the CEL on it's own, so I'm not taking much consideration into it.

    I guess my next step it is to take it back BUT before I do so I want to do some basic checks myself. I'm going to start with spraying some carb cleaner around bank 2 intake manifold. I did replace the intake gaskets last year when I replaced both Knock Sensors, so it's possible their may be a problem there.

    Any other suggestions?
  2. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts

    Bank 2 is passenger side, did it say position 1 or 2?

    Position 1 would be on the y pipe or exhaust manifold, If it's position 2 then that's the after the cat one. Just out of curiousity did they do ANY welding at all on that exhaust?? If they did then they should have unplugged all the 02 sensors before welding, and let the vehicle run and blow the weld fumes out. If they did weld in then I would say they fugged up your 02 sensors, and cost you uneccesary money for there mistake.
  3. SoundZman

    SoundZman Rockstar 100 Posts

    Well the Too Lean code didn't specify any specific o2 sensor position...I can't say how exactly the shop installed the cats & muffler but I can say I stopped by at one point and the down pipe was completely off the truck, also my mechanic mentioned they would have to drop the whole exhaust in order to replace the cats.

    I guess I stand corrected, I cleared the code last night since I know I wouldn't be able to get it back in until next week. I thought I would just see if the code would come back over the next 4 days, drove about 5 miles before the CEL came back on. Pulled it, and to my surprise, it was a P0101 (MAF Performance code).

    Prior to my drive last night, I did spray some throttle body cleaner around the both intake gaskets (as much as I could get to) which resulted in no fluctuation in idle.

    I did notice where this P0101 code began when I cleaned my MAF sensor & replaced the air filter at the same time. I did use MAF Sensor cleaner and allowed it to dry outside of the vehicle for a couple hours before I reinstalled it. I starting to wonder the off the self brand air filter from Kragen, may be what's causing my P0101....any thoughts on that?

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

    .........For A TROUBLE CODE P0101

    Technical Description,

    Mass Air Flow Seonsor(MAF)......Circuit Range/Performance Problem,

    What does that mean?
    Basically this means that there is a problem with the Mass Air Flow (MAF) sensor or circuit. The PCM detects that the actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value for more than 4.0 seconds. Other MAF sensor circuit DTC trouble codes are P0101, P0102, P0103 and P0104,

    You will likely not notice any serious drivability problems, although there may be symptoms

    Possible Solutions,

    • Inspect for the following conditions:
      An incorrectly routed harness--Inspect the harness of the MAF sensor in order to verify that it is not routed too close to the following components:
      - The secondary ignition wires or coils
      - Any solenoids
      - Any relays
      - Any motors
    • A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any vacuum leaks downstream of the MAF sensor.
    • A wide open throttle (WOT) acceleration from a stop should cause the MAF sensor g/s display on the scan tool to increase rapidly. This increase should be from 6-12 g/s at idle to 230 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.
    • The barometric pressure (BARO) that is used in order to calculate the predicted MAF value is initially based on the MAP Sensor at key ON.
    • When the engine is running the MAP Sensor value is continually updated near WOT. A skewed MAP sensor will cause the calculated MAF value to be inaccurate. The value shown for the MAP sensor display varies with the altitude. With the ignition ON and the engine OFF, 103 kPa is the approximate value near sea level. This value will decrease by approximately 3 kPa for every 305 meters (1,000 feet) of altitude.
    • A high resistance on the ground circuit of the MAP Sensor can cause this DTC to set.
    • Any loss of vacuum to the MAP sensor can cause this DTC to set.


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