The anti-lock braking system (ABS) is the one responsible in controlling your Mercedes Benz C220's braking ability under various driving conditions. An important part of this system is the ABS speed sensor that monitors your tires and makes sure that each wheel is properly rotating. It keeps the on-board computer (OBC) or the control module (ECM) updated on every moment of the car. It may be performing a simple task but this component could end up affecting not only your ABS system but also the transmission, speedometer, power steering, and cruise control. That's why it's important to keep yourself aware of what causes problems in your ABS speed sensors so you can fix the problem before it gets worse.
If your car's computer shows incorrect output, this could be caused by a dirty sensor probe. This problem with a dirty sensor probe can be easily solved by cleaning it off with a rag and a good quality contact cleaner. If the ABS sensor is working but the output is still incorrect, then you may have a problem with a break or a short in the sensor's wires. The problem is most likely near the sensor because that part is the circuit's dirtiest area.
When you are testing your sensors and the reading displays too high or too low results, act on it immediately. A reading that shows "O.L." or displays resistance that is higher than what's normal indicates that the internal circuit is electrically open. If the reading shows zero Ohms or is lower than it's supposed to be, then that means you have a shorted internal circuit. If you get these results from your sensor tests, it would be best to go for a replacement.
If your ABS speed sensor disables your car's traction and stability control systems, this could be caused by a wiring problem or terminal corrosion. Sometimes it can also result to abnormal breaking that can be easily noticed at slow speeds. These problems are usually the result of a failure in the interaction between the traction control system and the anti-lock brake system module.