Methods and systems are provided for waking up a powertrain control module of an engine-driven vehicle during engine soak to perform an offset test of an exhaust NOx sensor. In one example, a method includes determining a duration to delay waking up the powertrain control module based on exhaust temperature at vehicle-off, waking up the powertrain control module after the duration has expired, and then initiating heating of the NOx sensor. After the NOx sensor lights off, heating continues for an additional duration before offset testing of the NOx sensor is performed.

Methods and systems are provided for adjusting a voltage of a heated oxygen sensor (HEGO) so that the heated oxygen sensor is controlled to a desired temperature as the HEGO ages. In one example, a method generates a requested heated oxygen sensor electrode impedance for control and then adjusts the voltage responsive to the requested heated oxygen sensor electrode impedance for control.

Methods and systems are provided for adjusting a voltage of a heated oxygen sensor (HEGO) so that the heated oxygen sensor is controlled to a desired temperature as the HEGO ages. In one example, a method generates a requested heated oxygen sensor electrode impedance for control and then adjusts the voltage responsive to the requested heated oxygen sensor electrode impedance for control.

An air-fuel ratio detection device 1, 1 comprises: a sensor element 2, 2 including a sensor cell 10; a voltage application circuit 40, 40 applying voltage to the sensor cell; a current detector 42, 42 detecting an output current of the sensor cell; an air-fuel ratio calculating part 61 configured to calculate an air-fuel ratio of an exhaust gas; and a parameter detecting part 62 configured to detect or calculate a temperature correlation parameter correlated with a temperature of the sensor element. The air-fuel ratio calculating part is configured to calculate the air-fuel ratio of the exhaust gas based on the temperature correlation parameter and the output current detected when a predetermined voltage is applied to the sensor cell.

A method for monitoring an exhaust-gas sensor in which it is determined whether at least one monitored event has occurred by evaluating at least one heat quantity supplied to and/or withdrawn from the exhaust-gas sensor during a period of time, in particular under consideration of a change in the heat quantity stored by the exhaust-gas sensor that occurs during the period of time.

A particulate matter detection system has a particulate matter detection sensor, a current detection part and a control circuit part. The particulate matter detection sensor has an accumulation part, a pair of electrodes and a heater part. The control circuit part performs switching of a detection mode and a burning mode. When the burning mode being switched to the detection mode, the control circuit part supplies a lower voltage between the pair of electrodes, which is lower than an usual voltage used in the detection mode, and detects a current detected by the current detection part as the offset value I. In the detection mode, the control circuit part subtracts the offset value I from the detected current value to correct the detected current value.

Methods and systems for evaluating whether or not a fuel amount that is greater than a threshold has been release to an engine via fuel injectors when the fuel injectors are commanded off are presented. In one example, an oxygen sensor is activated and engine cranking is prevented until a pumping current of the oxygen sensor is proportionate to a concentration of oxygen sensed via the oxygen sensor so that released fuel may be observed during engine starting.

A control device of an internal combustion engine comprises a heater control part configured to set a target temperature of the electrochemical cell and control the heater so that a temperature of the electrochemical cell becomes the target temperature. The heater control part sets the target temperature to a first temperature when water injection by the water injection device is not being demanded after a predetermined time elapses from startup of the internal combustion engine, and sets the target temperature to a second temperature when an operating state of the internal combustion engine is in a water outflow state where water injected by the water injection device reaches the exhaust passage without going through combustion of air-fuel mixture in the combustion chamber. The second temperature is higher than the first temperature.

Methods and systems are provided for activating a universal exhaust gas oxygen (UEGO) sensor activation during each of a pre-delivery phase and a post-delivery phase of a vehicle. In one example, a method may include during the pre-delivery phase, following an engine start, using a lower current flowing via a heater coupled to the UEGO sensor to heat the UEGO sensor and during the post-delivery phase, following an engine start, once exhaust temperature reaches a threshold temperature, using a higher current flowing via the heater coupled to the UEGO sensor to heat the UEGO sensor.

A filter malfunction determination apparatus includes a calculator that calculates, upon determination that a rapid output increase has occurred, an amount of change of a parameter value output from a sensor before and after the rapid output increase. The calculator calculates, based on the calculated amount of change, a correction value for correcting at least one of the parameter value output from the sensor and a malfunction determination threshold. The filter malfunction determination apparatus includes an offset corrector configured to perform, based on the correction value, offset correction of at least one of the parameter value output from the sensor and the malfunction determination threshold after determination that the rapid output increase has occurred.