TSB: Buick Mystery Code

This bulletin applies to 2024-2025 Buick Envista vehicles. The CEL/MIL may be on with a service charging system message. DTC P0621 may be set as current or history.

GM Engineering is currently investigating the issue. If est results do not directly identify a functional fault, do not replace any parts at this time. Advise the customer that they may continue to drive the vehicle.