The present disclosure relates to a system, apparatus, and method for reconditioning a particulate matter sensor in an exhaust aftertreatment system that will resist poisoning. The system and method includes receiving particulate matter data indicating a state of the particulate matter sensor; determining that the particulate matter sensor is in a full state based on the particulate matter data; activating a heating element of the particulate matter sensor to a multiple of intermittent temperatures that clean the sensor pre-patory to the next measurement. By this manner, many reactive chemicals are removed before they can react with and poison the sensor materials.

A control device of an exhaust sensor comprises a battery voltage detection part detecting a voltage of a battery, and a heater control part setting a target temperature of an electrochemical cell and controlling the electric power supplied from the battery to a heater. The heater control part sets the target temperature to a first temperature after startup of the internal combustion engine until the voltage of the battery recovers to a predetermined voltage, and switches the target temperature from the first temperature to a second temperature when the voltage of the battery recovers to the predetermined voltage. The first temperature is a temperature lower than an operating temperature of the electrochemical cell and at least a lowest temperature at which a Leidenfrost phenomenon occurs at the protective layer. The second temperature is a temperature of the operating temperature or more.

A heater is provided that includes at least one resistive heating element having a material with a non-monotonic resistivity vs. temperature profile and exhibiting a negative dR/dT characteristic over a predetermined operating temperature range along the profile. The heater can include a plurality of circuits disposed in a fluid path to heat fluid flow.

Methods and systems are provided for a particulate matter sensor positioned downstream of a diesel particulate filter in an exhaust system. In one example, a particulate matter sensor assembly may include an outer stepped tube, an inner stepped tube positioned within the outer tube, and a plate having sensor element positioned inside the inner tube, the inner and the outer tube generating a step in the assembly. The step may block larger contaminants and water droplets, and thereby stopping them from impinging on the sensor element positioned within the assembly.

A sensing assembly comprises a sensor housing having a sensing end and a coupling end opposite the sensing end. A sensing element and a heating element are disposed within the sensor housing. A tip cover and coupling end cover removably coupled to the ends of the sensor housing. The tip cover and coupling end cover are configured to be uncoupled from the sensor housing to enable removal of at least one of the sensing element, the heating element, or an integrated sensing/heating element from the sensor housing, and replacement with at least one of a new sensing element or a new heating element, the tip cover and coupling end cover configured to be recoupled to the sensor housing after at least one of the new sensing element or the new heating element is disposed in the sensor housing.

In a control device for a particulate matter detection sensor, a voltage value acquiring unit acquires a sensor voltage value which is a value of a voltage being applied across a pair of electrodes in the particulate matter detection sensor. A current value acquiring unit acquires a sensor current value which is a value of a current flowing between the electrodes. An output unit outputs a PM current value corresponding to the amount of deposit of particulate matter on an element part of the particulate matter detection sensor. States which the particulate matter detection sensor is determined to be in by a state determining unit include a sensor failure state and a PM-deposited state. The state determining unit determines whether the particulate matter detection sensor is in the sensor failure state or the PM-deposited state based on the sensor voltage value and the sensor current value.

Methods and systems are provided for a NO.sub.x sensor. In one example, a method includes heating a NO.sub.x sensor during a vehicle off in response to a cumulative heat energy applied to the NO.sub.x.

Disclosed is a method for control of an activation of a fluid sensitive sensor of an exhaust treatment system arranged for treating an exhaust stream, which includes: determining an exhaust temperature and an exhaust mass flow for the exhaust stream; determining if there is liquid fluid present in the exhaust stream at the fluid sensitive sensor, respectively, based on: 1) an elimination time function, wherein the elimination time function is based on the determined exhaust temperature and the determined exhaust mass flow; and 2) a corresponding lengths of a time period needed to eliminate a predetermined amount of liquid fluid from the exhaust stream; and controlling an activation of said fluid sensitive sensor based on the determination of if there is liquid fluid present in the exhaust treatment system at the fluid sensitive sensor.

A diagnostic system (10) is provided and includes a sensor (24) disposed downstream from an exhaust gas aftertreatment system. Also included in the diagnostic system (10) is a central diagnostic unit (35) configured to diagnose a condensation condition associated with the sensor (24) for mitigating a sensor failure due to water condensation on the sensor (24), the central diagnostic unit (35) performing the diagnosis on the condensation condition based on water storage and release information related to a component of the exhaust gas aftertreatment system. The sensor (24) is activated based on the water storage and release information.

A method for operating a heater system including a resistive heating element having a material with a non-monotonic resistivity vs. temperature profile is provided. The method includes heating the resistive heating element to within a limited temperature range in which the resistive heating element exhibits a negative dR/dT characteristic, operating the resistive heating element within an operating temperature range that at least partially overlaps the limited temperature range, and determining a temperature of the resistive heating element such that the resistive heating element functions as both a heater and a temperature sensor. The resistive heating element can function as a temperature sensor in a temperature range between about 500° C. and about 800° C., and the non-monotonic resistivity vs. temperature profile for the material of the resistive heating element can have a local maximum and a local minimum.