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 wheel angle sensor (657): Function: Notes
The steering wheel angle sensor comprises a ring gear (1) mounted on the steering column shaft. Two gears with different numbers of teeth (2a has 28 teeth and 2b 26 teeth) engage this ring gear. Each gear has a permanent magnet (3a and 3b) and sensor, the resistance of which depends on the magnetic field.
Since the two gears 2a and 2b have different numbers of teeth, the relative positions of the permanent magnets will be unique for each steering wheel angle. Accordingly, the position of the steering wheel can be transmitted on the P-bus. This information is used by the ESP control module.
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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.
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