CITROEN DS3 Owner's Handbook Manual page 174

Reactivation
Press the "ECO OFF" switch again.
The system is active again; this is confirmed
by the switch warning lamp going off,
accompanied by a message in the screen.
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 working 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 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
battery must be done by a CITROËN
dealer or a qualified workshop.