Honkin’ the Benz
2011 Mercedes-Benz C350 vehicles equipped with a 3.5L engine and electric power steering (ES) may hear a honking noise when steering to the limit stop.
The cause is the controller or motor of the ES being excited and vibrating. Performing a software update on the steering control unit will reportedly eliminate the noise.
Use SDS XENTRY software version 07/2012 or higher.