Check Engine Light Code P0172 Lean

2005 Chevy Monte Carlo 3.4l V6.
Check engine light. Scanned code P0172 - rich. Replaced first o2 sensor. What else can the problem be if the o2 sensor graph is still dropping and raising then staying low .

Answer: A rich code, but with an oxygen sensor showing lean is odd.
I would suspect that this is not an oxygen sensor problem, but possibly a programming issue with the PCM

There sis a bulletin for a false rich code. Re-flash of the computer would be needed. The dealer would need to do that. A check of your VIN is the only way to see if your vehicle is involved in this bulletin. This is not a recall, just a service bulletin, also known as a TSB.


Silverado IAT Sensor Wire Colors

What are the color of the wires for IAT sensor on the MAF plug 2000 Chevrolet Silverado 6.0L Vortec V8.

Answer: The black wire is the sensor ground. The ground is internal to the PCM.
The TAN (terminal B)wire is the 5 volt reference / sensor signal wire. Also from the PCM.


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  • Guest - Tom

    In reply to: Guest - Stacy

    A code p0172 - is a rich condition. That would explain the black smoke. Black smoke means you're burning way too much fuel. I would check the fuel pressure regulator. That is most common on your car.

  • Guest - Stacy

    I have a 02 pace car Monte Carlo it have black smoke and it have the service engine soon light an the check engine light on an I no I need a oil change but my car is running rough an idleing really high then drop low with very bad gas mileage an it haves a very hard start p.s. the only real way my car would even crank is if you push all the way down on the gas an I took it to oralleys and the code P0172 I changed the throttle body an p.s I just got the car about 2 months ago an I love it but I just need to no what to do thanks guys....

  • Guest - Bob

    In reply to: Guest - Tomeka

    We need the code numbers you got to help with your problem.

  • Guest - Tomeka

    In reply to: Guest - Tomeka

    I have a 2010 pontiac g6 and i went today to auto zone to get a diagnostic because yesterday my check engine light came on and so i after that i put $20 87gas in it then today i upgraded and put $30 89gas in it made sure that the gas cap was on secure.
    <br />the diagnostic readsif bank one and two codes set togther suspect fuel pressure or maf sensor. 2)oxygen sensor defected. 3) ignition misfire repair 4)fuel injector problem.

  • Guest - Tomeka

    I have a 2010 pontiac g6 and i went today to auto zone to get a diagnostic because yesterday my check engine light came on and so i after that i put $20 87gas in it then today i upgraded and put $30 89gas in it made sure that the gas cap was on secure.