Patent ID: 7533519

Claim:
A method for conditioning performance of an emission control system test on a showing of temperature sensor functionality at engine start-up, the method comprising: at engine start-up, processing temperature data from temperature sensors at respective spaced apart locations along a flow path containing one or more emission control devices to develop a first set of data values each representing a respective temperature difference between a respective pair of locations; processing the first set of data values to develop a second set of data values each representing the difference between a respective pair of data values of the first set; processing each data value of the second set and a respective reference value to develop a third set of data values; and conditioning performance of the test on the third set of data values disclosing both that at least one of the sensors is indicating a respective sensed temperature no greater than a predetermined temperature for the respective sensor at and below which it is permissible for the test to be performed and that no sensor is concurrently indicating a respective sensed temperature determined to be indicative of its non-functionality.