I have the same thing, I'll check bearings and probably have the rotors turned. Sometimes after some hard braking the rotors sill get hard spots and that can make a noise, as well as eat grooves in your pads.

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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