BMW E90 models have an advanced radiator fan control, which uses a Pulse-width-modulated or PWM signal to regulate the fan speed.
Your Volvo, like any other car, uses a blower motor to push the air into the cabin. The blower motor operation is regulated by a control unit.
Leaking oil cooler gaskets are a common problem that affects most BMW engines made in the last 20 years.
This article will cover replacing two separate parts, a crankshaft sensor and a crankcase ventilation system, as both require identical steps.