Mercedes E-class service interval reset.

This is E-Class W211 service interval reset procedure (look at photo 1), it's also can apply on other model as well.

1st, turn your key to 1st stage (There is 3 stages for MB key lock, the last stage is to ignite engine)

2nd, Continuously press the knob 3 time (Look at the finger I pointed), ensure your cluster is on SPEED MODE "0KM/H". 

After that it will bring you to "UB:12.5V", For your information this is your battery voltage.

choose "Confirmation" and "Full service" and you have done the manual service interval reset.

But sometime it will show you this (check out the photo below). What I've encountered usually is mileage manipulated therefore required DAS to further check the problem.