One problem related to brake sensor has been reported for the 2004 Mercedes Benz E320. The most recently reported issues are listed below.
On 12/16/2020 while driving the brakes on my vehicle failed. A red warning triangle appeared on the vehicle message board stating the cars braking ability was severely reduced and to stop driving immediately. I was able to drift to the side of the road without incident and had the vehicle towed to my mechanic. The mechanic could find no mechanical reason for the brake failure. The red warning light was gone and the brakes were functioning normally. Online research revealed an extended warranty/recall for the year, make and model of the car related to brake failure. Mercedes will replace the sensortronic brake control module (sbc) free provided the correct codes are evident when they diagnose the car. (safety recall #2005110001 I believe) my mechanic said that there are no codes showing for the brakes and the brakes are now functioning. My online research has shown that this can be an intermittent problem and the dealerships are reluctant or will not replace the sbc if there are no codes. After contacting mercedes the car is being towed to the dealership as I type this. I am hopeful that mercedes will do the correct thing and replace their admittedly flawed brake module but it isn't looking good as they said if the correct codes do not appear they will not replace. The insane idea that I am expected to continue to drive the vehicle until the brakes fail again in order to get them replaced is unacceptable. I'm in a no win situation.