B0102high severityBody

Immobilizer Transponder Authentication Failure

on 2018 GMC Acadia 3.6L V6 · FWD

What this code means

The immobilizer detected a transponder signal but authentication failed. The key code does not match the stored code.

Symptoms

  • Engine cranks but will not start
  • Security light solid on
  • Key rejected by system

Common causes

  • Key not programmed to this vehicle
  • Immobilizer module lost key memory
  • Aftermarket key with incorrect code
  • Immobilizer control module failure

Diagnostic steps

  1. Try all registered keys
  2. Check key programming status
  3. Attempt key relearn procedure
  4. Scan immobilizer module codes
  5. Verify VIN match in immobilizer

Repair notes

Reprogram key to vehicle using manufacturer procedure. May require dealer tool.

Other Body codes on this vehicle

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