Abstract: A method for diagnosing the performance of a refueling event detection system for a vehicle is provided. The method includes the steps of a) determining a fuel change amount based on a difference of an indicated fuel amount and a previously indicated fuel amount, b) determining a consumed amount of fuel consumed by the engine since a prior refueling event was detected, and c) diagnosing the performance of the refueling event detection system based on the consumed amount and the fuel change amount.

Abstract: A method for diagnosing the performance of a refueling event detection system for a vehicle is provided. The method includes the steps of a) determining a fuel change amount based on a difference of an indicated fuel amount and a previously indicated fuel amount, b) determining a consumed amount of fuel consumed by the engine since a prior refueling event was detected, and c) diagnosing the performance of the refueling event detection system based on the consumed amount and the fuel change amount.

Abstract: 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.