CITROËN DS 5 Handbook page 36

Less than 600 miles (1 000 km)
remain before the next service is due
Example: 500 miles (900 km) remain before
the next service is due.
For a few seconds after the ignition is switched
on, the instrument panel screen indicates:
After the message disappears, the spanner
remains on alongside the mileage recorder as
a reminder that a service must be carried out
soon.
Service overdue
For a few seconds after the ignition is switched
on, the spanner flashes to indicate that
the service must be carried out as soon as
possible.
Example: the service is overdue by 300 miles.
When the ignition is switched on, the instrument
panel screen indicates:
The spanner remains on alongside the
mileage recorder to indicate that a service is
overdue.
With BlueHDi Diesel versions, the
Service warning lamp also comes on
when the ignition is switched on.
The spanner may come on if you have
exceeded the period since the last service,
as indicated in the manufacturer's service
schedule.
For BlueHDi Diesel versions, the
spanner may also come on early,
according to the level of deterioration
of the engine oil, which depends on the
driving conditions in which the vehicle
is used.