Some 2018-2023 Mustang vehicles (non-Shelby GT-350) may exhibit various concerns with the active exhaust system. These may include Exhaust Mode Selection Not Available messages, and/or illuminated malfunction indicator lamp (MIL) with diagnostics trouble codes (DTCs) P26C5, P26C6, P26FE, P2BF9, P2BFB, P26C7, P2BF5, P2BF8, P2BFD and/or P2BFA. This may be due to an improperly seated exhaust system. To correct the condition, follow the Service Procedure to diagnose the tailpipe actuator.
