Malfunction Indicator Lamp (MIL) Illuminated, DTC P31E8, P31DB, P31D4 and/or P31E2 Set – 2020-2021 Cadillac CT4 & CT5

This service bulletin provides a repair procedure to correct a customer concern of

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NHTSA ID Number: 10198892

Manufacturer Communication Number: 21NA130

Summary

This service bulletin provides a repair procedure to correct a customer concern of Malfunction Indicator Lamp (MIL) Illuminated, DTC P31E8, P31DB, P31D4 and/or P31E2 Set.

Condition

Some customers may comment that the MIL is illuminated.

Some technicians may find one or more of the following DTCs set in the Engine Control Module (ECM):

  • P31D4: Exhaust Flow Control Valve – Position Signal Exceeds Upper Limit — Bank 1
  • P31DB: Exhaust Flow Control Valve Stuck Open — Bank 1
  • P31E2: Exhaust Flow Control Valve – Position Signal Exceeds Upper Limit Bank 2
  • P31E8: Exhaust Flow Control Valve Stuck Open Bank 2

Cause

This condition may be caused by old firmware or fail-safe spring failure within exhaust valve actuator.

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