A method and a corresponding apparatus for carrying out a reference measurement on a sensor of an internal combustion engine of a motor vehicle during an overrun phase of the internal combustion engine, in order to detect measurement errors of the sensor. Provision is made that future overrun phases of the internal combustion engine, and the duration of the overrun phases, are predicted on the basis of route data; and that a reference measurement on the sensor is carried out only when the predicted duration of the overrun phase is long enough to carry out the reference measurement completely. With the method and apparatus presented, the functioning of sensors can be monitored during an overrun phase of a motor vehicle having an internal combustion engine.