<p>An apparatus includes an operating conditions module that interprets a number of compressor operating parameters; a compressor flow module that determines a compressor inlet flow in response to the number of compressor operating parameters; and a fresh air flow module that provides a fresh air flow value in response to the compressor inlet flow. The operating conditions module further interprets a current mass air flow value, and the apparatus further includes a mass air flow sensor trimming module that adjusts a mass air flow sensor drift value in response to the current mass air flow value and the fresh air flow value. The apparatus includes a diagnostics module that determines a mass air flow sensor is failed in response to the current mass air flow value and the fresh air flow value.</p>
