Duramax Tuner Delete Kit

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FAQS

No. Once the Duramax tuner delete kit is installed, the custom tuning remains in the ECU even if you unplug the tuner. However, the vehicle will default to the “No Power” mode unless the tuner is plugged in to switch levels.

These codes often indicate incomplete DEF delete or sensor misconfiguration. Make sure all sensors are unplugged and that you’re running the latest firmware version for your lml duramax tuner.

A: No. The L5P ECM is encrypted, and traditional tuners like Mini Maxx V1/V2 will not work. You must use the OBDii Flash Delete Tuner or Tuner for GM Duramax L5P, both designed specifically for 2017–2023 engines.

Try removing the tuner, disconnecting battery terminals, and using a 10A charger to fully recharge both batteries. Reconnect everything and try again. Also, verify that the SD card is inserted fully and contains the correct update files.

On some LML and L5P trucks, improper cable routing near the instrument cluster or radio harness can cause CAN bus interference. Reroute cables away from these systems and reboot. In most cases, unplugging the tuner temporarily restores function.

  • #399/#327 – SD card issue or voltage loss during flash
  • C747 – Locked ECM or incompatible vehicle (common on commercial chassis models)
    Solution: Recheck SD card format (FAT32, ≤8GB), ensure you’ve selected the correct platform, and use a constant-voltage battery charger.