Patent ID: 6862518

Claim:
A method for monitoring a cooling fluid circuit ( 16 ) of an internal combustion engine ( 10 ), in which an electronic control unit ( 42 ) compares a measured actual value of a temperature of the engine ( 10 ) to a desired value of the temperature, which is determined from a stored model that depends on the energy throughput of the engine ( 10 ), and the control unit ( 42 ) sets a first error signal if the deviation of the actual value of the temperature from the desired value of the temperature exceeds a predetermined amount, characterized in that a second error signal is set, which indicates a possible lack of antifreeze if a starting temperature is below the freezing point of water, a first error signal was present, the first error signal is no longer present after a predetermined time, which is a function of the starting temperature of the engine ( 10 ), and a built-in energy balance exceeds a threshold, which is a function of the starting temperature of the engine ( 10 ).