2005 Mercedes C-Class Owner's Manual - Page 296

Operation Maintenance Resetting the maintenance service indicator In the event that the maintenance service on your vehicle is not carried out by an authorized Mercedes-Benz Center, you can have the maintenance service indicator reset. The automotive maintenance facility carrying out the maintenance service will find the information for resetting the maintenance service indicator in the maintenance-relevant information for your vehicle. Such information is available from either your authorized Mercedes-Benz Center or directly from Mercedes-Benz. i If the maintenance service indicator was inadvertently reset, have an authorized Mercedes-Benz Center correct it. Only reset if the proper maintenance service has been performed. Resetting the system without performing the proper service as called for by the maintenance service indicator will result in engine damage and/or other vehicle damage not covered by the Mercedes-Benz Limited Warranty. 294