P1621

The Transmission Control Module (TCM) contains various types of memory to gather and share information internally. At shut down, the TCM stores information in memory to prepare for the next ignition cycle. When the TCM cannot communicate internally, DTC P1621 sets. DTC P1621 is a type A DTC.

DTC PARAMETERS
DTC P1621 will set if the TCM cannot communicate internally for a proper shut down.

DIAGNOSTIC AIDS
The only possible repair is TCM replacement. Remember to program the replacement TCM with the correct software and calibration.