A control system and method to monitor an intake air temperature sensing
circuit for an internal combustion engine is shown. The electronic
controller is connected to the intake air temperature sensing circuit,
coolant temperature sensor, and a plurality of other engine sensors. The
controller determines whether the measured intake air temperature changes
in response to a change in actual intake air temperature, based upon the
engine operating conditions and the measured intake air temperature. The
controller determines whether the measured intake air temperature is
representative of actual intake air temperature, based upon the measured
intake air temperature, the coolant temperature, and at least one engine
operating condition. The invention is an element of an on-board
diagnostic system, typically related to vehicle emissions.