The invention relates to an electrochemical gas sensing apparatus for sensing one or more analytes, such as NO.sub.2 and/or O.sub.3, in a sample gas and a method of using same. The apparatus uses Mn.sub.2O.sub.3 as a filter for ozone. The Mn.sub.2O.sub.3 may take the form of a powder which may be unmixed, mixed with various PTFE particles sizes, formed into a solid layer deposited onto a membrane and/or pretreated with NO.sub.2.

Provided is a method for manufacturing a gas sensor capable of securing airtightness without a chip in a sensor element. The method includes a step of obtaining an assembled body constituting the gas sensor, including steps of causing one end of the sensor element to abut to a positioning member for positioning the sensor element; applying a force F1 to the annularly-mounted members including a powder compact annularly mounted to the sensor element under a state that the sensor element is positioned and thereby compressing the powder compact so as to fix the sensor element inside of the tubular body, applying a force F2 larger than the force F1 to the annularly-mounted members under a state that the sensor element is not positioned and thereby further compressing the powder compact, so as to hermetically seal inside of the tubular body.

Provided is a method for manufacturing a gas sensor which suppresses a defective product caused by a defective posture of a sensor element therein. The method includes a step of obtaining an assembled body constituting the gas sensor, including steps of: causing one end of the sensor element to come to abut to a positioning member for positioning the sensor element; and applying a first force to the annularly-mounted members including a powder compact annularly mounted to the sensor element under a state that the sensor element is positioned and thereby compressing the powder compact so as to fix the sensor element inside of the tubular body, and the compression is performed while constraining the sensor element in a predetermined constraining region in the other end side of the sensor element.

Methods and systems are provided for detecting NOx sensor degradation based on results from a NOx sensor self-diagnostic (SD) test performed after a key-off event. In one example, a method may comprise waiting a duration to perform a SD test of a NOx sensor after a key-off event until engine operating conditions stabilize and reach a set of qualifying conditions. One or more SD tests may be performed after waiting the duration, but outputs generated under conditions where one or more of a temperature at the sensor is greater than a threshold, and an oxygen concentration is outside a threshold range, may be excluded when determining whether or not the NOx sensor is degraded.

A device and method for calibrating a NO delivery device using NO and NO.sub.2 measurements, without using a known standard.

A diagnostic system and method for diagnosing the performance of a particulate matter (PM) filter of an exhaust system each involve receiving, by a controller from at least one sensor, a gas component measurement of exhaust gas flowing through the exhaust system and the PM filter. The controller calculates a conversion efficiency of the gas component by the PM filter and compares the calculated conversion efficiency to a predetermined conversion efficiency threshold indicative of an expected conversion efficiency of a flow-through catalyst. The controller then determines whether the PM filter is cracked or damaged based on the comparison between the calculated conversion efficiency and the predetermined conversion efficiency threshold.

A sensor element includes a base part including a plurality of oxygen-ion-conductive solid electrolyte layers stacked; a measurement-object gas flow part for introduction and flow of a measurement-object gas through a gas inlet; an inner oxygen pump electrode disposed on an inner surface of the measurement-object gas flow part; and a measurement electrode disposed on the inner surface of the measurement-object gas flow part. The inner oxygen pump electrode includes: a region (A) including an electrode end close to the gas inlet, and a region (B) including an electrode end far from the gas inlet. A content rate of an activity reducing metal in a metal material in the region (A) is higher than that in the region (B). A ratio of the length of the region (A) of the inner oxygen pump electrode to the length of the inner oxygen pump electrode is 15% to 90%.

A sensor element includes a base part including a plurality of oxygen-ion-conductive solid electrolyte layers stacked; a measurement-object gas flow part for introduction and flow of a measurement-object gas through one end part in a longitudinal direction of the base part; a main pump cell including an inner main pump electrode disposed on an inner surface of the measurement-object gas flow part, and an outer pump electrode; a target-gas-decomposing pump cell including a target-gas-decomposing pump electrode disposed at a position farther from the one end part than the inner main pump electrode, and an outer pump electrode; a residual-oxygen-measuring pump cell including a residual-oxygen-measuring electrode disposed at a position farther from the one end part than the inner main pump electrode, and an outer pump electrode; and a reference electrode. The target-gas-decomposing pump electrode comprises a metal material that has catalytic activity of decomposing a target gas to be measured.

A control method of a gas sensor including a sensor element and an activity determining part includes a temperature raising step of heating the sensor element by a heater of the sensor element to raise a temperature of the sensor element up to an active temperature at which the activity determining part determines that the sensor element is in a measurable active state; a prior driving step of raising the temperature of the sensor element by the heater from the active temperature up to a steady driving temperature, and operating a main pump cell and a measurement pump cell of the sensor element to detect NOx in the measurement-object gas; and a steady driving step of maintaining the temperature of the sensor element by the heater at the steady driving temperature, and operating the main pump cell and the measurement pump cell to continuously detect NOx in the measurement-object gas.

An aftertreatment system configured to reduce constituents of an exhaust gas produced by an engine comprises an aftertreatment component and an optical assembly. The optical assembly comprises an optical emitter configured to emit light onto a face of the aftertreatment component, and an optical detector configured to detect light reflected from the face of the aftertreatment component. A controller is configured to determine at least one of an amount of NOx gases or an amount of ammonia on the face of the aftertreatment component based on an optical parameter of the detected light that has reflected from the face of the aftertreatment component.