I supplied an independent with pads, discs, and brake sensors for a brake job.( O5 E320 CDI) When I got the car, the Brake Wear Indicator was showing in the dashboard. He tried to clear it with a Baum scanning tool and could not. I was in a hurry and took the car. Later, I jacked it up and disconnected the electrical harness to the SBC. I started with the left front and checked the continuity of each brake sensor. Left front was okay. I had purchased a backup set of sensors from MB ( about $7.00 each ). I noticed that the right front sensor was different from the OEM MB sensor. I am not sure of the brand of sensor that I received with my pads and discs, but they were not MB. I replaced the right front sensor with the OEM sensor. After each of the replacements I would go to the car and turn the key to the number 2 position and check if the brake sensor warning was cleared. So far, it was not. When I got to the right rear, I could see that the sensor was not plugged in. I replaced the sensor with the OEM MB and checked the dash again, and the fault had cleared, however, I had a check engine light. I have an OBD 2 scanner and program and it said that the fault was the speed sensor. It probably occurred when I turned the key to the number 2 position with the electrical harness to the SBC disconnected. I think that if I had waited to finish each of the sensors, then plugged in the SBC harness and checked to see of the brake wear indicator had cleared, I would not have gotten the check engine light. I cleared the fault with my program and everything is back to normal. Moral of the story. If you get aftermarket pads and discs, that is okay, but get the MB sensors. They fit snugger and will stay there. Also, that particular warning cannot be cleared by an OBD 2 scanner. It has to have a complete electrical circuit through at least the right front and right rear.

Footnote: I have 2 05 CDI's and I got the same Brake Wear Indicator warning in the other car after a brake job at the same independent. When I jacked the car up and looked at the right front wheel, there was no sensor installed. When I looked at the sensor that was supposed to go there( a non OEM part ), it was too narrow to fit the probe in the small hole and go into the slot. I am heading for MB this morning to buy another OEM sensor that should fit. I guess I have to find another independent!!!!!!!

This just keeps getting better!!! The OEM Brake sensor from MB doesn't fit into the front brake pad. It is too narrow. Now I am thinking that this guy put the back pads on the front and the front on the back. wow!!!!

 

Just finished doing the brake job on a 2003 E500 and disconnected the SBC by pulling up on the harness then removing the torx 25 screw holding in the harneess then carefully prying the harness off. I was also left with the Brake wear sensor malfunction and have yet to clear it . will check sensors are working but if you are doing this job look closely at the four front pads . The hole or recepticle for the wear sensors are in two different locations make sure to get them right.