A method for surface of a conscious of a coolant - temperature sensor of a motor vehicle with an internal combustion engine and an auxiliary heater, as well as control device

摘要

A method for monitoring a coolant - temperature sensor of a motor vehicle with an auxiliary heater, whereinin the case of a cold start (t = t_St) an internal combustion engine of the motor vehicle by means of a coolant - temperature sensor comprises an actual value (tco_is = Tco_St) a coolant temperature (tco), is determined, withthe coolant - temperature sensor in the case of an to the cold start, (t = t_St) of the internal combustion engine directly and with respect to time for a short period of time (t t_min. t₀) subsequent lowering of the actual value (tco_is) the coolant temperature (tco), as a functional coolant - temperature sensor is diagnosed, whereinchronologically after the cold start of the internal combustion engine (t t_St) or after the start of the coolant pump a course monitoring of the coolant temperature (tco) is performed, wherein the course of monitoring with a narrow time grid at least up to a further increase (t ≧ t_min.) the coolant temperature (tco) or at least up to an end (t ≧ t₀) of the sag (t₀) the coolant temperature (tco) and the course of monitoring is carried out by evaluating a surface (a) a heating curve of the coolant temperature (tco), which, from the heating curve after the cold start of the internal combustion engine (t = t_St) or of the coolant pump to the reaching of a coolant temperature (tco₀ = Tco_St) during a cold start of the internal combustion engine (t = t₀ = t_St), is limited; takes place, wherein a comparatively for this purpose in each case, a current value ascertained, averaged, minimum and / or maximum value is.