P1621high severityPowertrain
PCM Memory Performance (Long Term Memory Error)
on 2022 Cadillac XT5 3.6L V6 · FWD
What this code means
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.
Other Powertrain codes on this vehicle
P0001
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P0002
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P0003
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P0004
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P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1