31 00... Information on replacing shock absorbers: Situation
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2013 BMW 335xi, 2013 BMW 335is, 2013 BMW 335i, 2012 BMW 335xi, and 2012 BMW 335is. However, it is still accessible from the selected car via links, so may be relevant.
When a shock absorber is faulty on one side (leaking, noises, limit values exceeded on the shock tester), often both shock absorbers on the axle in question are replaced.