N18: Service Engine Soon Lamp (MIL) May Come On at High Altitude. The Service Engine Soon lamp (MIL) is illuminated and engine power output is reduced. This could only occur only in areas high above sea level (greater than 5,000 feet) and more frequently with colder outside temperatures. The following faults will be stored in the DME, and no engine mechanical problems are found. * 2C56 - Charging pressure control, plausibility Pressure too high * 2C58 - Charging pressure control, switch-off: pressure build-up blocked Unfavorable DME software