Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.