the oxygen sensors 66 and 68 allow the ecu 28 to monitor air fuel ratios also over a wide range thereby allowing ecu 28 to determine a value associated with the exhaust gas entering and exiting the nox adsorber 18 additional embodiments contemplate oxygen sensors positioned at other locations for example in a system including a saline nox catalyst oxygen sensors could be positioned to sense input and output flow of the saline nox catalyst the oxygen sensors 66 and 68 can enter into a learning mode or autozero mode in such modes the oxygen sensors can adaptively learn the appropriate calibrations for an aftertreatment system to which they are coupled learning modes may include calibration zeroing and other operations which assist in or provide increased accuracy and or reduced error in measurement and or estimation of oxygen levels and or in adapting oxygen sensor operation to a mode of system operation engine 12 includes a fuel injection system 90 that is connected with and controlled by the ecu 28 fuel injection system 90 delivers fuel into the cylinders of the engine 12 various types of fuel injection systems may be utilized in the present invention including but not limited to pump line nozzle injection systems unit injector and unit pump systems high pressure common rail fuel systems common rail fuel injection systems and others the timing of the fuel injection the amount of fuel injected the number and timing of injection pulses are preferably controlled by fuel injection system 90 and or ecu 28 with reference to fig3 there is illustrated an oxygen sensor learning mode control diagram 300 which can be executed by a controller such as ecu 28 oxygen sensor learning control diagram 300 includes block 500 which receives inputs 501 502 and 503 and.