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Thread: Clearing p0102 and 0121 Codes

  1. #1
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    Default Clearing p0102 and 0121 Codes

    Got a service engine soon light and it looks like the codes are P0102 and 0121.

    My question is, how do I clear the codes to return things to normal and remove the SES light?

    I want to do this so I can start trouble shooting the problems.

  2. #2
    Lifetime Member GMPX's Avatar
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    P0102 Mass Air Flow (MAF) Sensor Circuit Low
    P0121 Throttle Position (TP) Sensor 1 Performance

    If they just popped up for no reason I think you need to check some wiring, clearing them doesn't fix the root cause of the DTC's setting in the first place.
    I no longer monitor the forum, please either post your question or create a support ticket.

  3. #3
    Joe (Moderator) joecar's Avatar
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    P0121:
    if you installed a cam with more overlap, you have to edit the MAP sanity table/parameters; otherwise you have to troubleshoot.

    P0102:
    unless you intentionally failed the MAF, you have to troubleshoot.

  4. #4
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    Quote Originally Posted by joecar View Post
    P0121:
    if you installed a cam with more overlap, you have to edit the MAP sanity table/parameters; otherwise you have to troubleshoot.

    P0102:
    unless you intentionally failed the MAF, you have to troubleshoot.
    Car has a big cam in it and I think the the MAP tabe was adjusted for this. The MAF isn't hooked up at all so I know that issue.

    I just need to get rid of the codes so I have a clean slate to trouble shoot from and can drive the car without any issues. I tried what I thought was the correct method and the codes didn't clear.

    i did some research on the 0121 code and it seems like it could be a wiring/TPS issue and I want to drive the car around to see if the TPS is doing anything strange.

  5. #5
    Joe (Moderator) joecar's Avatar
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    If TPS/wiring is good, take a closer look at your logged MAP (look at closed throttle, and idle) and see where it lies in relation to the Min/Map MAP sanity tables.

    The MAF DTC will be present until you connect the MAF.

  6. #6
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    Quote Originally Posted by joecar View Post
    If TPS/wiring is good, take a closer look at your logged MAP (look at closed throttle, and idle) and see where it lies in relation to the Min/Map MAP sanity tables.

    The MAF DTC will be present until you connect the MAF.
    I don't see anything obvious with the wiring. I'm going to log the car Friday when I drive to a meet to see if I see anything odd.

    The car is tuned via speed density so the MAF isn't hooked up. That code has been cleared in the past so I'm not to worried.

    I figured out how to clear the codes so the car will run normal and not in limp mode for now.

    The issue arose at the track when the tree dropped and I mashed the gas to the floor. Wondering if the TPS is going bad if that type of action would cause it to go into limp mode and throw the code.

  7. #7
    Lifetime Member GMPX's Avatar
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    Quote Originally Posted by waggz View Post
    The car is tuned via speed density so the MAF isn't hooked up. That code has been cleared in the past so I'm not to worried.
    If you want to run speed density you cannot disable the MAF DTC, the ECM needs to know the MAF failed so it can default to SD. Normally you would just disable the MIL from being turned on but leave the DTC active.
    This is one of the reasons why some people won't tune SD because you can't pass a smog check with a DTC set and for SD to work correctly a MAF DTC will always be there.
    I no longer monitor the forum, please either post your question or create a support ticket.

  8. #8
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    Quote Originally Posted by GMPX View Post
    If you want to run speed density you cannot disable the MAF DTC, the ECM needs to know the MAF failed so it can default to SD. Normally you would just disable the MIL from being turned on but leave the DTC active.
    This is one of the reasons why some people won't tune SD because you can't pass a smog check with a DTC set and for SD to work correctly a MAF DTC will always be there.
    Okay, that makes sense.

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