CITROËN DS 4 Handbook page 420

QUESTION
With the engine off, the When the engine is switched off, the audio system operating time
audio system switches off depends on the state of charge of the battery.
after a few minutes of use. The switch-off is normal: energy economy mode is activated
automatically to preserve the state of charge of the vehicle's
battery. (See the "Energy Economy Mode" section).
The message "the audio In order to protect the installation if the surrounding temperature
system is overheated" is too high, the audio system switches to an automatic thermal
appears on the display. protection mode leading to a reduction of the volume or stopping of
the playing of the CD.
ANSWER SOLUTION
Start the vehicle's engine to increase the battery
charge.
Switch the audio system off for a few minutes to
allow the system to cool.