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Thread: Emissions fail: monitors not ready

  1. #1
    Tuner in Training
    Join Date
    Jul 2020
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    24

    Emissions fail: monitors not ready

    I failed emissions. It said monitors were not ready. Well I checked tune and it should pass. It's been 5 days about 250 miles and 3/4 tank of fuel.
    These things still day incomplete.

    Does that mean it will still fail emissions? Do they need to say complete to pass and if so. What do I need to do?

    Basically fuel, catalyst and oxygen sensor say incomplete.
    Thank you

  2. #2
    Senior Tuner TheMechanic's Avatar
    Join Date
    Jan 2014
    Location
    SoCal
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    1,533
    A monitor is a test. It has either run/complete or not run/incomplete. It is not a pass or fail it is just if the test has completed for whatever system needed the test. If you look at each monitor it needs certain things to be ready to take the test. Example you need the VSS to function to take a EGR test because it is used while it is running/driving down the road. If it isn't driving the test will not start. Miles, and days driven has no bearing on monitors. If you keep a full tank or an empty tank all the time the monitor for EVAP will NEVER run. You could drive for years that way.
    As to Kalifornia then yeah if you don't have all your monitors you fail. Even though you may have NOTHING wrong with your vehicle. You did not mention what that was so just google search your vehicle with "drive cycle" and you will see what you need to do. Cold start, specific idle time specific acceleration rate, specific maintained speed for specific minimum time, slowing down at a specific rate etc. etc. If they don't run you may have programming issues that are causing this or maybe a system that is skewed or out of spec. Had a truck one time I spent several hour trying to figure out why it wouldn't run and pass EVAP. Even forced with my Tech2Win and MDI2. It was a skewed fuel tank pressure sensor that was off JUUUST enough to say it was in a constant pressure but not enough to set the code.