A method and system for monitoring a mass flow controlled by an actuator

The method monitors the mass flow along a mass flow line (5) of an IC engine (10), e.g. an exhaust gas feed back line, controlled by a setting element (1), by measuring the temperature at the latter and by calculating a second value for the temperature at the setting element in dependence on a number of engine parameters. The direction of the mass flow is provided from the difference between the 2 temperature values. An Independent claim for a device for monitoring a mass flow along a mass flow line for an IC engine is also included.