How to clear the DTCs (check engine light) on your Cummins without using a code reader.
NOTE: Depending on which flash is on your PCM, there is a chance that this procedure will not work. In that case, it is best to use an OBD-II scanner to clear the codes.
- Put the key in the ignition with doors closed.
- Cycle the key FIVE times from the OFF position to the RUN position without cranking the engine. Leave in the RUN position on the FIFTH cycle. Note: The RUN position is TWO clicks while the ACCESSORY position is only ONE click.
*Example: KEY IN (OFF) – RUN – OFF – RUN – OFF – RUN – OFF – RUN – OFF – RUN
- This will clear any DTCs that are currently active or stored in the PCM.