The how to reset the Assyst, Procedure.

1)Turn the key to position 2 in the ignition lock and immediately press button 000.0 twice within the space of one second.

2)Turn the key to position 0 in the ignition lock.

3)Press and hold button 000.0 Turn the key to position 2 in the ignition lock. Keep button 000.0 pressed.

4)Service message with current remaining distance or remaining time appears.

5)After about 10 seconds, an acoustic signal will sound and the service display with the new starting distance or starting time appears for about 10 seconds.

6)Release button 000.0

Your service indecator is now set.

This only applies to the W168 Mk1 and Mk1 Facelifted A-Class only, IE: A140, A160, A190 & A210 Petrol and the A160CDI, A170CDI diesel engines.
This will not work on a W169 model which is from late 2004 onwards.