CITROËN DS4 Owner's Handbook Manual page 216

Reactivation
Press the "ECO OFF" switch again.
The system is active again; this is confirmed
by the switch warning lamp going off and a
message in the instrument panel.
The system is reactivated automatically
at every new start using the key.
Operating fault
In the event of a malfunction with the system,
the "ECO OFF" switch warning lamp flashes,
then comes on continuously.
have it checked by a CITROËN dealer or a
qualified workshop.
In the event of a fault in STOP mode,
the vehicle may stall. It is then necessary to
switch off the ignition and start the engine
again using the key.
Maintenance
Before doing anything under the
bonnet, deactivate the Stop & Start
system to avoid any risk of injury
resulting from automatic operation of
START mode.
This system requires a specific battery with a
special specification and technology (reference
numbers available from a CITROËN dealer or a
qualified workshop).
Fitting a battery not listed by
CITROËN introduces the risk of malfunction of
the system.
The Stop & Start system makes use
of advanced technology. All work on
this type of battery must be done only
by a CITROËN dealer or a qualified
workshop.