Abstract: A system includes: a NOx sensor; and a controller configured to: increase an amount of O2 in a chamber of the NOx sensor; interpret one or more values of a parameter indicative an amount of O2 and/or NOx measured by the NOx sensor; determine if the one or more values of the parameter exceed a threshold value; and indicate a failure of the NOx sensor responsive to the one or more values of the parameter do not exceed the threshold value.

Abstract: A system includes: a NOx sensor; and a controller configured to: increase an amount of O2 in a chamber of the NOx sensor; interpret one or more values of a parameter indicative an amount of O2 and/or NOx measured by the NOx sensor; determine if the one or more values of the parameter exceed a threshold value; and indicate a failure of the NOx sensor responsive to the one or more values of the parameter do not exceed the threshold value.

Abstract: A system includes: a NOx sensor; and a controller configured to: increase an amount of O2 in a chamber of the NOx sensor; interpret one or more values of a parameter indicative an amount of O2 and/or NOx measured by the NOx sensor; determine if the one or more values of the parameter exceed a threshold value; and indicate a failure of the NOx sensor responsive to the one or more values of the parameter do not exceed the threshold value.

Abstract: A system includes: a NOx sensor; and a controller configured to: increase an amount of O2 in a chamber of the NOx sensor; interpret one or more values of a parameter indicative an amount of O2 and/or NOx measured by the NOx sensor; determine if the one or more values of the parameter exceed a threshold value; and indicate a failure of the NOx sensor responsive to the one or more values of the parameter do not exceed the threshold value.

Abstract: An aftertreatment system comprises an exhaust reductant storage tank and a SCR system including a catalyst fluidly coupled thereto. The aftertreatment system also includes a controller configured to interpret an output signal indicative of a catalytic efficiency of the catalyst. The output signal is filtered using a fast filter to obtain a fast filter response signal, and also using a slow filter to obtain a slow filter response signal. It is determined if the fast filter response signal exceeds a first threshold and if the slow filter response signal exceeds a second threshold. In response to determining that the fast filter response signal exceeds the first threshold, and the slow filter signal response exceeds the second threshold, an indication is provided that an improper exhaust reductant is present in the storage tank.

Abstract: Diagnostic processes for determining whether a NOx sensor is in a stuck-in-range failure mode may be performed when the NOx sensor reaches an operational temperature and before the oxygen pumps of the NOx sensor are activated and/or during operation. The processes may include interpreting values of a parameter indicative an amount of O2 and/or NOx measured by the NOx sensor. The processes include determining if the values of the parameter exceed a threshold value and indicating a failure of the NOx sensor responsive to the values not exceeding the threshold value. In some implementations, the processes may include increasing an amount of O2 in a chamber of the NOx sensor. Increasing the amount of O2 in the chamber of the NOx sensor may include deactivating an oxygen pump of the NOx sensor or reducing an amount of O2 removed via an oxygen pump of the NOx sensor.

Abstract: An aftertreatment system comprises an exhaust reductant storage tank and a SCR system including a catalyst fluidly coupled thereto. The aftertreatment system also includes a controller configured to interpret an output signal indicative of a catalytic efficiency of the catalyst. The output signal is filtered using a fast filter to obtain a fast filter response signal, and also using a slow filter to obtain a slow filter response signal. It is determined if the fast filter response signal exceeds a first threshold and if the slow filter response signal exceeds a second threshold. In response to determining that the fast filter response signal exceeds the first threshold, and the slow filter signal response exceeds the second threshold, an indication is provided that an improper exhaust reductant is present in the storage tank.

Abstract: Diagnostic processes for determining whether a NOx sensor is in a stuck-in-range failure mode may be performed when the NOx sensor reaches an operational temperature and before the oxygen pumps of the NOx sensor are activated and/or during operation. The processes may include interpreting values of a parameter indicative an amount of O2 and/or NOx measured by the NOx sensor. The processes include determining if the values of the parameter exceed a threshold value and indicating a failure of the NOx sensor responsive to the values not exceeding the threshold value. In some implementations, the processes may include increasing an amount of O2 in a chamber of the NOx sensor. Increasing the amount of O2 in the chamber of the NOx sensor may include deactivating an oxygen pump of the NOx sensor or reducing an amount of O2 removed via an oxygen pump of the NOx sensor.