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Thread: 0x7E9: U0100 - Lost Communication With ECM/PCM A (Permanent)

  1. #1
    Potential Tuner
    Join Date
    Dec 2016
    Posts
    7

    0x7E9: U0100 - Lost Communication With ECM/PCM A (Permanent)

    why do i only see this in hp tuners no check engine light. Is this an issue with software?
    car seen to run fine.

  2. #2
    Potential Tuner
    Join Date
    Dec 2016
    Posts
    7
    re flashed with stock tune code went away. its just weird that the check engine light did not come on..

  3. #3
    HPT Employee Mark@HPTuners's Avatar
    Join Date
    Jun 2014
    Location
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    432
    The U0100 code is common after a re-flash. The reason it did not trip the light is because the code is Permanent and not Current/Pending. More information on Permanent DTCs can be found here:

    http://www.hptuners.com/forum/showth...nd-VCM-Scanner