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1998 BUICK CENTURY
3.1L V6•FWD•AUTOMATIC•gas
4 active safety recalls on this vehicle — view recalls
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Repairs0Labor486Torque2155Fluid7DTC969Battery1Maintenance0Recalls4
P1621high severityPowertrain

PCM Memory Performance (Long Term Memory Error)

on 1998 Buick Century 3.1L 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

  1. Check battery voltage and charging system
  2. Attempt PCM reflash/reprogram
  3. Check for aftermarket tuning devices
  4. Test PCM with factory scan tool
  5. 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.

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