Supersedes Technical Service Bulletin Group 91 number 13-06 dated September 12, 2013. Customer reports sound system ?pops? and loses audio for a few seconds (for vehicles with base sound system) or sound system loses audio for a few seconds and returns on its own (for vehicles with Bose or Bang & Olufsen sound system). If the sound does not return on its own, or is accompanied by relevant DTCs in the vehicle, another issue may be present. Verify the root cause before proceeding with this bulletin. HD radio does not output in Stereo. This bulletin only applies to vehicles with Navigation Plus (PR Number 8DY). The applicable vehicles can be clearly identified by the MMI control panel in the center console. Continual improvements to MMI software provides solutions to issues experienced in the field.