Tracks and displays current sensor data like engine rpm, calculated load value, coolant temperature, fuel system status, vehicle speed, short term fuel trim, long term fuel trim, intake manifold pressure, timing advance, intake air temperature, air flow rate, absolute throttle position, oxygen sensor voltages/associated short term fuel trims, fuel system status, fuel pressure etc. It reads diagnostic trouble codes, both generic and manufacturer-specific, and displays their meaning (over 3000 generic code definitions in the database), clears trouble codes and turn off the mil ("check engine" light)