A gas sensor control apparatus (300) including a control section (61) which executes a first receiving process (STEP 1) for receiving a first detection result output from a mixed-potential-type ammonia detection section (42) for detecting ammonia contained in a gas under measurement and corresponding to the concentration of ammonia, a second receiving process (STEP 1) for receiving a second detection result output from an oxygen detection section (2) for detecting oxygen contained in the gas under measurement and corresponding to the concentration of oxygen, a first concentration calculation process (STEP 3) for calculating a first ammonia concentration of the gas under measurement based on the first detection result and the second detection result, and a pressure correction process (STEP 6) for correcting the first ammonia concentration based on pressure information obtained from an external device (220), thereby obtaining a second ammonia concentration of the gas under measurement.

Various embodiments include a method for operating an internal combustion engine with a three-way catalytic converter with lambda control, comprising: monitoring a NO.sub.x sensor for a lambda value downstream of the converter; setting a threshold value determining a lambda setpoint value upstream of the converter using the difference between the setpoint value of the electrical signal and the measured electrical signal if the signal is below the threshold; if above the threshold value, determining the lambda setpoint value upstream of the converter using the difference between a NH.sub.3 setpoint value of the NO.sub.x sensor and the measured NH.sub.3 signal of the NO.sub.x sensor; and if the measured NH.sub.3 concentration is higher than the NH.sub.3 setpoint value, increasing the lambda setpoint value upstream of the converter and, if the measured NH.sub.3 concentration is lower than the NH.sub.3 setpoint value, reducing the lambda setpoint value upstream of the converter.

An exhaust gas after-treatment system for an internal combustion engine includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having treated exhaust gas output. An oxides of nitrogen (NOx) sensor is coupled to treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH.sub.3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a NOx concentration signal to an electronic control unit operatively associated with the exhaust gas after-treatment system and the internal combustion engine. CLO output at least includes an exhaust gas NOx concentration estimate and the ECU is arranged to be operable upon the NOx concentration estimate to control exhaust gas after-treatment system and internal combustion engine to effect an overall reduction in actual NOx concentration with the exhaust gases.

The abnormality diagnosis system 1, 1, 1 of an ammonia detection device 46, 71 comprises: an air-fuel ratio detection device 41, 72 arranged in the exhaust passage 22 at the downstream side of the catalyst 20; an air-fuel ratio control part 51 configured to control an air-fuel ratio of exhaust gas; and an abnormality judgment part 52 configured to judge abnormality of the ammonia detection device. The air-fuel ratio control part performs rich control making the air-fuel ratio of the inflowing exhaust gas richer than a stoichiometric air-fuel ratio. The abnormality judgment part judges that the ammonia detection device is abnormal if, after start of the rich control, an output value of the ammonia detection device does not rise to a reference value before the air-fuel ratio detected by the air-fuel ratio detection device falls to a rich judged air-fuel ratio richer than a stoichiometric air-fuel ratio.

In a method of performing active control between a lean operation state and a rich operation state on a vehicle engine including a three way catalyst in an exhaust path, on a downstream side with respect to the three way catalyst in the exhaust path, a limited current type NOx sensor having NH.sub.3 interference and also capable of detecting a change in an oxygen concentration on the downstream side is disposed, and an operation state of the vehicle engine is switched between a lean operation state and a rich operation state at a timing when a detection of a change in an oxygen concentration in an exhaust air flowing out from the three way catalyst or a detection of NOx or NH.sub.3 is performed first by the NOx sensor.

A gas sensor control apparatus (300) including a control section (61) which executes a first receiving process (STEP 1) for receiving a first detection result output from a mixed-potential-type ammonia detection section (42) for detecting ammonia contained in a gas under measurement and corresponding to the concentration of ammonia, a second receiving process (STEP 1) for receiving a second detection result output from an oxygen detection section (2) for detecting oxygen contained in the gas under measurement and corresponding to the concentration of oxygen, a first concentration calculation process (STEP 3) for calculating a first ammonia concentration of the gas under measurement based on the first detection result and the second detection result, and a pressure correction process (STEP 6) for correcting the first ammonia concentration based on pressure information obtained from an external device (220), thereby obtaining a second ammonia concentration of the gas under measurement.

A control apparatus mounted on a diesel vehicle including an oxidation catalyst, a selective reduction catalyst, and a gas sensor includes an activation determination section, a concentration computation section, and a deterioration determination section. The concentration computation section computes the concentration of flammable gas from a sensor output in a period during which the activation determination section determines that the oxidation catalyst is not in the activated state and computes the concentration of ammonia gas from the sensor output in a period during which the activation determination section determines that the oxidation catalyst is in the activated state. The deterioration determination section determines whether or not the oxidation catalyst has deteriorated, on the basis of the concentration of the flammable gas computed by the concentration computation section.

Systems and apparatuses include an a system including an engine out sensor, an exhaust sensor, and one or more processing circuits comprising one or more memory devices coupled to one or more processors. The one or more memory devices are configured to store instructions thereon that, when executed by the one or more processors, cause the one or more processors to receive the engine out sensor information from the engine out sensor, receive the exhaust information from the exhaust sensor, determine the aftertreatment system characteristic based on the exhaust information, compare the aftertreatment system characteristic to an exhaust condition, determine an acceptable input value when the aftertreatment system characteristic meets the exhaust condition, and control at least one of a fuel system actuator and an air handling actuator to achieve the acceptable input value.

Methods and/or systems for operating an exhaust-gas aftertreatment system of an internal combustion engine include: setting the internal combustion engine to a diagnostic operating mode with relevant diagnostic operating parameters of the internal combustion engine are set to correspond with diagnostic default values; inducing a targeted, defined NH.sub.3 and/or NO.sub.x concentration change upstream of the filter; measuring the NH.sub.3 and/or NO.sub.x concentration change downstream of the filter; providing a correlating concentration comparison value; evaluating the concentration change on the basis of the respective concentration comparison value and predefined limit values; and diagnosing the SCR particle filter as defective if the evaluation yields that the concentration comparison value has overshot a predefined limit value.

A fuel content detection system is disclosed. The fuel content detection system may include an engine control module (ECM) to receive a measurement of a parameter. The parameter may correlate with an amount of a substance in a fuel that is being consumed in an engine. The ECM may determine an estimation of the parameter based on a model. The model may use a predetermined value associated with the amount of the substance, and the engine may be configured to consume a designated type of fuel that includes an amount of the substance that corresponds to the predetermined value. The ECM may determine, based on the estimation and the measurement not being within a threshold range, that the fuel is not the designated type of fuel and perform an action associated with the engine.