See also:

Detection zone
...

Reactivation
These systems are reactivated automatically each time the ignition is switched back on or from 30 mph (50 km/h). Press the "ESP OFF" button again to reactivate them manually. ...

Impact detection zones
A. Front impact zone. B. Side impact zone. Triggering of the airbag(s) is accompanied by a slight emission of harmless smoke and a noise, due to the activation of the pyrotechnic cartridge inc ...