A heating apparatus for a motor vehicle including a heat exchanger having a wall for separating a heated exhaust gas from a heat exchange medium, a conveyor mechanism for conveying the heat exchange medium along the wall, and a protective mechanism for protecting the heater against overheating. The protective mechanism determines the mass flow of the heat exchange medium delivered by the conveyor mechanism when the heater is actuated so that the danger of overheating the heater is reliably detected when the delivery of the heat exchange medium is dammed.