Abstract: A system for measuring NOx content of an exhaust gas produced includes at least one controllable valve operable to direct exhaust gas to a NOx sensor only when measurement of the NOx content is desired and to otherwise expose the NOx sensor to ambient air. A control circuit controls the operation of the at least one valve and determines the NOx content of the exhaust gas based on sensory data received from the NOx sensor.

Abstract: An accessory control system for a vehicle which includes an engine, cooling fan driven by the engine and a selectively-operable, power-requiring accessory includes an electronic logic control module which is packaged within a logic control box and which is electrically connected between various sensors and various power-requiring accessories. The accessory control system further includes a first signal output line which is electrically connected between the logic control module and a power-requiring accessory, such as a combine unloader. Also connected to the logic control module is an engine temperature sensor which operates on a thermocouple principle and is connected to a relay within the logic control module. If the engine temperature is below a threshold level then the logic control module is able to disengage the cooling fan so as to make additional horsepower available for operation of the power-requiring accessory.