You can reset the service code for your '05 Mercedes Benz from your home garage, saving a trip to the mechanic or dealership. A service light illuminates on the instrument panel when a sensor sends a trouble code to the on-board diagnostics (OBD) computer. Trouble codes are used to diagnose problems with a vehicle. After you read the codes and service the vehicle, you can reset the code using an OBD II scan tool. This small computerized device can be purchased from any auto parts retailer. You must reset the service code after the vehicle has been serviced or you may damage the computer.
Find the diagnostic port that is the same shape and size as the connector on the OBD II scan tool. This port can be found on the driver's side dashboard near the steering column.
Plug the OBD II scan tool into this port. Put the key into the ignition and turn it to the "ACC" position, but don't start the engine. This should power on most scan tools. If not, find the on/off switch on the scan tool and turn it on.
Wait while the scan tool retrieves the codes. Look for a command that says "Delete Codes" or "Erase Codes" or something similar. Select this command and wait for the tool to do the job.
Unplug the scan tool and start the engine. Verify that the "Service Engine Soon" light on the instrument panel has turned off.
