Turn the ignition on but do not start the vehicle. Hold the milage reset button in the dash for approx 10 seconds at the same time. The display will show the wrench symbol and the message "CFG 1" or "CFG2" or "CFG3" press the button to the required setting the press it again and hold it for at least five seconds, this will store the setting and clear the service message. I will check the service intervals later but, for a camper I think it is "CFG1"