Mercedes-Benz W204 ABS tone ring and wheel speed sensor
Mercedes-Benz W204: can the ABS tone ring cause an ABS, ESP or transmission fault?
Yes. A rusted or broken ABS tone ring gives the sensor a weak or intermittent signal. The result can be ABS and ESP lights, transmission jerking and fault code P0730, as well as engine revs rising at idle. Replacing the ring removed the symptoms.
Mercedes-Benz W204: which fails more often, the tone ring or the sensor?
When the disturbance is related to wheel speed, the fault is more likely in the ring than in the sensor. The ring often suffers from rust, which detaches the magnetic rubber from the metal. That is why the ring and the sensor are checked first.
Mercedes-Benz W204: the ABS lights are still on after replacing the wheel speed sensor, why?
In diagnosis the sensor signal can still be implausible. The fault was fixed by a new sensor from the original manufacturer (ATE), and aftermarket sensors do not always work. Check the fault with fault codes.
Mercedes-Benz W204: can I replace the ABS tone ring myself?
The brake system is safety-critical, so have a workshop do the job and check the result. Not all control arms necessarily have to be removed, but installing the ring requires a clean hub and the correct angle.