Patent ID: 7857508

Claim:
A method for monitoring the functionality of a temperature sensor that can deliver an electrical signal as a function of the measured temperature and is disposed, in particular, in the cooling water circuit of an internal combustion engine, comprising: characterizing the sensor as possibly faulty if the sensor indicates, upon engine shutdown, at least a maximum value of the cooling fluid temperature; determining a first gradient of the cooling fluid temperature, measured by the possibly faulty sensor, up to a first point in time after engine shutdown, and characterizing the sensor as fault-free if the gradient exceeds a minimum value; determining a second gradient of the cooling fluid temperature, measured by the possibly faulty sensor, between the point in time and a point in time after engine shutdown, and characterizing the sensor as fault-free if the second gradient exceeds a minimum value; and determining the cooling fluid temperature measured by the possibly faulty sensor at a point in time after engine shutdown, and characterizing the sensor as fault-free if the cooling fluid temperature falls below a maximum value.