Cathode filter replacement algorithm in a fuel cell system

A fuel cell system that includes a compressor for providing cathode air to the cathode side of a fuel cell stack and an air filter for filtering the air sent to the compressor to prevent particulates and other contaminants from entering the compressor and the fuel cell stack. The fuel cell system also includes a mass flow meter that measures the flow of air to the compressor and a pressure sensor that measures the pressure of the airflow at the output of the compressor. An electronic compressor map is provided that defines the operating characteristics of the compressor. By knowing the flow through the compressor and the pressure at the outlet of the compressor, an algorithm can determine where on the compressor map the compressor is operating, and from that determine the inlet pressure to the compressor, which in turn shows whether the air filter is clogged or otherwise damaged.