Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Steering assistance
The steering assistance takes the form of conventional hydraulic steering (rack-and-pinion construction).
The speed-dependent steering assistance (= Servotronic) has been available in the E61 series since 03/2004. E63 and E64 have Servotronic as standard from start of series production. Servotronic has been standard on the E60 since 03/2005.
Active Steering and Servotronic are co-ordinated. Servotronic is controlled by the AL control unit.
The AL control unit actuates the Servotronic valve and the ECO valve in the power-steering pump via the Safety and gateway module (SGM). The ECO valve in the power-steering pump regulates the volume flow in the power-steering pump.
This arrangement means that only the volume flow needed for steering assistance at any given time is actually provided. In this way, the ECO valve affects the power consumption of the power-steering pump. Fuel consumption and carbon dioxide emissions (CO2) from the vehicle's engine are reduced accordingly.
In vehicles without Active Steering, Servotronic is controlled directly by the safety and gateway module (except BMW 1 and 3-Series).
Clearly, therefore, the steering assistance and AFS are complementary, despite the fact that in terms of function, the two systems are fully independent of each other.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.