CITROEN DS4 Owner's Handbook Manual page 222

Reactivation
Press the "ECO OFF" switch again.
The system is active again; this is confirmed
by the switch warning lamp going off and the
display of a message.
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. All of
the instrument panel warning lamps
come on.
Depending on version, an alert
message may also be displayed asking
you to put the gear lever into position N
and put your foot on the brake pedal.
It is then necessary to switch off the
ignition, then restart the engine 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.