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Chev 2500 will not run on CNG if check engline light is on

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  • Chev 2500 will not run on CNG if check engline light is on

    We own a bi-fuel 2013 Chevrolet 2500. Anytime the check engine light comes on, the truck will not run on CNG. Is there a solution to get the truck to run on CNG even if the check engine light is on? A member of our family drives a Dodge truck for a company vehicle and it will still run on CNG even if the light is on. Thanks for your help.

  • #2
    Have you plugged in a scanner to read what OBD engine code is being set?


    • #3
      Yes we are getting two codes P2270 and P2272 (both O2 sensor related). Is there a way to delete/eliminate the O2 sensors?


      • #4
        Removing the O2 sensors will just cause even more codes to start setting, so don't do that...

        The codes indicate a lean burn condition, which means there is too much air / not enough fuel. So this code probably is being thrown and the check engine light is turning on when the truck is on CNG mode, correct? If so you should check to ensure there is enough CNG flowing to the fuel rail. You can do this with a fuel rail pressure gauge. I don't know what GM specified for the fuel rail pressure on CNG for this model, but generally its around 110 psi on most vehicles. Typical culprits for low or restricted fuel flow include:
        * Clogged CNG fuel filters (if this truck has low-pressure fuel filters between the regulator and engine fuel rail)
        * Bad pressure regulator
        * Other physical blockage in the gaseous fuel system

        Check out the listing of CNG repair facilities in Oklahoma here:

        Good luck and let us know how it goes.


        • #5
          Thanks for the information! Will definitely check the fuel rail pressure.


          • #6
            if the Dodge is CNG only then that explains why it runs with a CEL on.

            What codes are being thrown to trigger the CEL, google obd 2 scan can buy the cheap ones from autozone /oriellys etc... ive seen them online for under 20 bucks