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  1. #1

    Default 06 Silverado Engine Code that keeps coming back

    Hey everyone, I have an 06 Silverado that keeps throwing a double code. The code numbers are P2A01 and P2A04. Both codes come back as oxygen sensors, bank 1 sensor 2 and bank 2 sensor 2. When I look up the information on these codes, all it says is that they are performance codes. I have talked with several repair shops and none seem to know what this code is or what causes it. I was thinking exhaust leak, but cant find one. Could it be bad sensors since they both appear to have been replaced?

  2. #2

    mfleetwood's Avatar
    Join Date
    Jul 2010
    Denver, CO
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    From what I gathered, you have either bad sensors, or if the sensors were moved further downstream as a result of after-market headers being installed (IF it is also throwing a heater code). Below is the most thorough information I could find.

    __________________________________________________ __________________________________________

    DTC P2A01: HO2S Performance Bank 1 Sensor 2 , Post Cat. O2.
    • The Engine Run Time parameter is more than 5 minutes.

    • The ignition 1 Signal parameter is between 10-18 volts.

    • The MAF sensor parameter is between 3-50 g/s.

    • The Engine Speed parameter is between 500-5,000 RPM.

    • The Vehicle Speed parameter is between 24-132 km/h (15-82 mph).

    • The Fuel Level Sensor parameter is more than 10 percent.

    • The Short Term FT parameter is between -4 and +4 percent.

    • DTC P2A01 runs once per drive cycle when the above conditions are met for 1 second.


    • The control module detects that the sensor did not transition below 200 mV and above 730 mV during the passive test.

    • One of the following tests fail:

    Lean Intrusive Test
    - The control module detects that the sensor is more than 200 mV for 12 seconds.

    - The sensor is less than 200 mV.

    Rich Intrusive Test
    - The control module detects that the sensor is less than 730 mV for 12 seconds.

    - The sensor is more than 730 mV.

    • DTC P2A01 sets within 10 minutes when the above conditions are met.

    All things being equal, the o2 sensor is probably bad. It didn't set a heater code, so the heater side of the o2 is most likely good. You need a scanner to read the 02 sensor and see what is happening, but it's a good bet to be just a bad sensor.

    Mike (Denver, CO) - 2008 Sierra 1500 Z71 SLE 5.3L 4WD

    SUSPENSION: Rancho 4" Suspension Lift; Rancho RS9000XL Shocks; Rancho Skid Plates; Rancho MyRide Wireless Shock Controller;
    BFG All Terrain KO 315/70/17
    DRIVE TRAIN: 4.56 Gears; Detroit TrueTrac Differential; True Cool 40k Transmission Cooler
    PERFORMANCE: DiableSport Predator Tuner; Custom Tuned by Diablew; Magnaflow Exhaust; AFE Cold Air Intake
    ELECTRONICS: Kenwood DNX6180 Touchscreen; Subthump box w/10" Kicker; Driver Information Center (DIC); Rear View Camera
    ACCESSORIES: Westin Brush/Grill Gaurd; Westin Nerf Bars; Truxedo Tonneau; 20% Tint; Tow Mirrors w/Heat & Signals

  3. #3


    Thanks for the info. That is the same info I got from one repair shop. Think I may try replacing the O2 sensors. Will probably replace them with the sensors you dont have to put together, because it appears they used the ones you assemble yourself.

  4. #4

    mfleetwood's Avatar
    Join Date
    Jul 2010
    Denver, CO
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    Good luck and let us know how it goes.

  5. #5


    So I had my oil change today and found out that I have a crack in the driver's side cat... could this cause a double downstream O2 engine light?
    Robert - Indiana
    2006 Silverado Crew Cab LT Z71
    -Gibson Dual Cat-back

    Not much, but it sounds good!

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