DTC P1621: Powertrain Control Module Memory Performance: Description

Powertrain Control Module (PCM) checks the integrity of the non-volatile memory area of the Electrically Erasable Programmable Read-Only Memory (EEPROM). The PCM uses the EEPROM to store the information at key off. There are several locations where the information is stored within the non-volatile memory. If PCM detects a problem in one location of the EEPROM, the PCM will attempt to store the data in another location. If PCM runs out of valid places to store the information, DTC P1621 will set.