An apparatus and method for monitoring and diagnosing the coil temperature of a magnetorheological (MR) clutch connected to a power steering pump of a vehicle is disclosed. The apparatus includes a processing circuit, and a storage medium, readable by the processing circuit, for storing instructions for execution by the processing circuit for receiving a plurality of input signals representative of dynamic operating conditions relating to the vehicle, using the input signals to generate an output signal representative of a temperature of the coil of the MR clutch, determining from the output signal whether the temperature of the coil exceeds a threshold limit, and in response to the temperature of the coil exceeding a threshold limit, triggering at least one of a remedial action and a data storage algorithm.