Some 2020-2021 Mustang GT500 vehicles may experience erratic and harsh shifting at highway speeds and/or perceived lack of power when accelerating from a stop, with a powertrain malfunction (wrench) indicator and diagnostic trouble codes (DTCs) P1601 and/or P061A stored in the powertrain control module (PCM) while using SelectShift. This may be due to the software in the PCM. To correct the condition, follow the Service Procedure to reprogram the PCM.
