Common Problems in Mercedes Benz Active Noise Cancellation Systems

Mercedes-Benz has always been synonymous with automotive luxury and one of the pillars of that luxury is the Active Noise Cancellation (ANC) system. ANC technology works to make the cab a peaceful place by electronically modifying the unwanted road, wind and engine noise and generating anti-phase sound waves to cancel the ambient noise before it ever reaches your ears.

ANC technology consists of microphones, speakers and an advanced algorithm to generate the anti-phase sound waves and cancel the ambient noise before it can reach any part of your ears. Like any other complicated electronic system, the Mercedes-Benz ANC is not flawless.

Noise Amplification

The ANC system ends up enhancing some frequencies rather than canceling them. It occurs when the microphones in the system receive sound signals in the wrong way and the algorithm produces a sound wave that is in-phase instead of anti-phase with the noise source.

The sound comprises a deep resonant hum that drivers frequently report especially when traveling at high speed or on uneven roads. This symptom is often associated with microphone calibration drift over time, software algorithm errors or particularly after a partially completed over-the-air (OTA) update, broken or misplaced cabin microphones that feed false data.

This is usually fixed by re-flashing or recalibration of the microphone array by dealer software although in certain instances replacement of the microphones may be necessary.

Complete ANC System Failure

Others complain that the ANC system will cease operation without any warning lights or display an error on the instrument panel. The cabin becomes strangely noisier and the noise of the road and wind penetrates more than they should in a car of its category.

The root causes are usually a malfunctioning ANC control module (ECU), a blown fuse or faulty relay in the audio or comfort electronics circuit, loss of connection between the ANC module and the COMAND or MBUX infotainment system and corrupted software especially following battery disconnection or a voltage drop incident.

The fault is in most cases diagnosed and corrected by a hard reset of the electrical system of the vehicle or a STAR Diagnosis scan at a Mercedes-Benz dealership.

Wind Noise Sensitivity and Microphone Saturation

ANC systems are very dependent on cabin microphones that are at strategic positions like in the headliner, pillars and at the seat positions. These microphones have to constantly sample the noise environment although they are subject to being overwhelmed by strong, gusty winds or turbulence getting into the cabin.

Once microphone saturation has been reached then the system has trouble distinguishing between the real cabin noise and distortion in its own circuit.

The symptoms include crackling or static-like sounds from the speakers at low speeds, random changes between active and passive noise modes and sudden increases or decreases in perceived cabin noise.

Audio System interference

Mercedes-Benz ANC is closely integrated with the standard audio system with the car's speakers serving as the output medium for anti-noise signals. Although it is a very elegant integration but there may be interference in such a tight integration when there is a clash between the two systems.

The typical symptoms include distortion in the playback of music in low frequencies, a continuous low-frequency drone that can be heard through the speakers when no music is on and changes in volume during the playback of audio which tend not to be directly caused by the user.

The typical solution is software updates that recalibrate the balance between the ANC output and the audio system signal path which is normally provided by the regular MBUX system updates by Mercedes-Benz.

Conclusion

The Active Noise Cancellation system of Mercedes-Benz is an engineering marvel that helps to enhance the driving experience in Mercedes-Benz luxury cars. The complexity of the system allows it to be vulnerable to a variety of technical malfunctions such as the degradation of the microphones and the conflicts in the computer programs as well as the failure of the modules and amplification errors.

In case of any of these problems it is highly advisable to pay an early visit to an authorized Mercedes-Benz service center that has the STAR Diagnosis facility. You can visit our service center. We have state-of-the-art tools and equipment along with experienced technicians who will ensure your vehicle is properly diagnosed.

We at European Auto Tech are Plano area’s leading luxury auto service centre. Our auto repair & body shop specializes in European and Asian cars like Audi, BMW, Jaguar, Rover, Lexus, Mercedes, Mini, Porsche, Volkswagen and Volvo. Moreover.