PCM Memory Performance (Long Term Memory Error)
1995-2005 Pontiac Sunfire 2.2L I4
Description
The PCM detected an internal memory fault in its EEPROM (Electronically Erasable Programmable Read Only Memory). The PCM stores critical adaptive and calibration data in this memory.
Symptoms
- Check Engine Light
- Various drivability issues
- Possible stalling
- Possible no-start condition
- Loss of learned values
- Erratic behavior
Common Causes
- Internal PCM/ECM failure
- Low battery voltage during operation
- Battery disconnection during critical write operation
- Corrupted PCM software/calibration
- Aftermarket tuning device issue
Diagnostic Steps
- Check battery voltage and charging system
- Attempt PCM reflash/reprogram
- Check for aftermarket tuning devices
- Test PCM with factory scan tool
- Verify PCM software version
Repair Notes
Try PCM reprogramming first. If memory error persists, replace PCM. Ensure battery is fully charged before any PCM service.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
P1621 on Other Vehicles
Pontiac Aztek
2001-2005 3.4L V6
Pontiac Bonneville
1990-1999 3.8L V6
Pontiac Bonneville
2000-2005 3.8L V6
Pontiac Bonneville GXP
2000-2005 4.6L V8
Pontiac Bonneville GXP
2000-2005 4.6L V8 Northstar
Pontiac Bonneville SSEi
1992-1999 3.8L Supercharged V6
Pontiac Bonneville SSEi
1992-1999 3.8L V6 Supercharged
Pontiac Firebird
1993-1997 3.4L V6
Common Questions
What does code P1621 mean on a 1995-2005 Pontiac Sunfire?
P1621 stands for "PCM Memory Performance (Long Term Memory Error)". The PCM detected an internal memory fault in its EEPROM (Electronically Erasable Programmable Read Only Memory). The PCM stores critical adaptive and calibration data in this memory.
What are the symptoms of P1621 on a Pontiac Sunfire?
Common symptoms of P1621 include: Check Engine Light, Various drivability issues, Possible stalling, Possible no-start condition, Loss of learned values, Erratic behavior.
What causes P1621 on a 1995-2005 Pontiac Sunfire?
Common causes of P1621 include: Internal PCM/ECM failure, Low battery voltage during operation, Battery disconnection during critical write operation, Corrupted PCM software/calibration, Aftermarket tuning device issue.