CITROEN C4 Cactus Handbook & Instructions page 274

05 TRAFFIC
Diverting from a route
Press on Navigation to display the primary
page then go to the secondary page.
Select "Traffic messages".
Select "Diversion".
Select the diversion distance by pressing + or -.
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Select "Recalculate route". The route
will be modified in time and distance.
Select "Confirm".
The route may be diverted following the reception of a traffic
information message.