A control circuit includes a sweep circuit for supplying a sweep current to a gas concentration sensor, a current detection resistor for detecting a sensor current flowing in the gas concentration sensor, a calculation circuit for calculating an impedance of the gas concentration sensor based on the sensor current and an inter-terminal voltage of the gas concentration sensor, and a protective element for suppressing external noise from being applied to the sweep circuit and the calculation circuit. The sweep current is divided to flow in a first protective element and the gas concentration sensor. The sensor current is divided to flow in a second protective element and the current detection resistor. The calculation circuit calculates a loss current flowing to the first protective element or a second loss current flowing to the second protective element and calculates the sensor current based on the calculated current.

A controller is used for an air-fuel ratio sensor. The air-fuel sensor includes a detection element that detects an oxygen concentration, and a PWM-controlled heater that receives a PWM signal for temperature control of the detection element. The controller includes a resistance detection circuit configured to detect a resistance of the detection element, and a processor. The processor is programmed to generate the PWM signal for the heater based on the detected resistance such that the resistance of the detection element is kept at a predetermined target resistance, and determine whether a failure has occurred in the air-fuel ratio sensor based on a manner of time-series increase in duty cycle of the PWM signal.

A control system of an internal combustion engine comprises an air-fuel ratio sensor 40, 41 detecting an air-fuel ratio of exhaust gas, a current detecting device 61 detecting an output current of the air-fuel ratio sensor, a voltage applying device 60 applying voltage to the air-fuel ratio sensor, and a voltage control part 81 configured to control voltage applied to the air-fuel ratio sensor through the voltage applying device. The voltage control part is configured to set the applied voltage to a reference voltage determined so that the output current becomes zero when an air-fuel ratio of inflowing exhaust gas flowing into the air-fuel ratio sensor is a stoichiometric air-fuel ratio, and correct the reference voltage so that the output current detected by the current detecting device becomes zero when it is judged that the air-fuel ratio of the inflowing exhaust gas is the stoichiometric air-fuel ratio.

A system and method for identifying the condition of fluids inside a container, by means of a resistive element associated with a control unit of the resistive element, preferably used for identifying the condition of water for application in a fuel vehicle water injection system, but not limited to this application. The control unit of the resistive element is comprised of a processing unit capable of obtaining the reading of the resistance of a resistive element and processing the information for performing the identification of the condition of the fluid, and also the composition can use the resistive element as a heating element through a heater control unit when it is identified that the condition of the fluid is solid.

Vehicle oxygen sensor heater diagnostic techniques comprise, upon detection of a set of cold start conditions of the vehicle, measuring an initial resistance of each of a set of two or more oxygen sensor heaters and determining whether any of the measured initial resistances is outside of a nominal resistance range. In response to an outlier oxygen sensor heater being outside of the nominal resistance range, each of the set oxygen sensor heaters is provided with an equal voltage for a period, the resistance of each of the set of oxygen sensor heaters is monitored during the period, and a malfunction of the outlier oxygen sensor heater is detected or matured when a difference between its resistance and the resistances of the other oxygen sensor heaters after the period is greater than a calibrated threshold.

The present disclosure provides a method for predicting a fluid type, comprising sensing, by a first sensor, mass flow data of a fluid in an engine, wherein the first sensor operates based on a first fluid property; sensing, by a second sensor, mass flow data of the fluid, wherein the second sensor operates based on a second fluid property; and detecting, by a logic circuit of a controller, a percent difference in the mass flow data provided by the first and second sensors, the percent difference indicating that the fluid is comprised of at least a first fluid type.

Vehicle oxygen sensor heater diagnostic techniques comprise, upon detection of a set of cold start conditions of the vehicle, measuring an initial resistance of each of a set of two or more oxygen sensor heaters and determining whether any of the measured initial resistances is outside of a nominal resistance range. In response to an outlier oxygen sensor heater being outside of the nominal resistance range, each of the set oxygen sensor heaters is provided with an equal voltage for a period, the resistance of each of the set of oxygen sensor heaters is monitored during the period, and a malfunction of the outlier oxygen sensor heater is detected or matured when a difference between its resistance and the resistances of the other oxygen sensor heaters after the period is greater than a calibrated threshold.

The present disclosure provides a method for predicting a fluid type, comprising sensing, by a first sensor, mass flow data of a fluid in an engine, wherein the first sensor operates based on a first fluid property; sensing, by a second sensor, mass flow data of the fluid, wherein the second sensor operates based on a second fluid property; and detecting, by a logic circuit of a controller, a percent difference in the mass flow data provided by the first and second sensors, the percent difference indicating that the fluid is comprised of at least a first fluid type.

A control system of an internal combustion engine comprises an air-fuel ratio sensor 40, 41 detecting an air-fuel ratio of exhaust gas, a current detecting device 61 detecting an output current of the air-fuel ratio sensor, a voltage applying device 60 applying voltage to the air-fuel ratio sensor, and a voltage control part 81 configured to control voltage applied to the air-fuel ratio sensor through the voltage applying device. The voltage control part is configured to set the applied voltage to a reference voltage determined so that the output current becomes zero when an air-fuel ratio of inflowing exhaust gas flowing into the air-fuel ratio sensor is a stoichiometric air-fuel ratio, and correct the reference voltage so that the output current detected by the current detecting device becomes zero when it is judged that the air-fuel ratio of the inflowing exhaust gas is the stoichiometric air-fuel ratio.

The present disclosure provides a method for predicting a fluid type, comprising sensing, by a first sensor, mass flow data of a fluid in an engine, wherein the first sensor operates based on a first fluid property; sensing, by a second sensor, mass flow data of the fluid, wherein the second sensor operates based on a second fluid property; and detecting, by a logic circuit of a controller, a percent difference in the mass flow data provided by the first and second sensors, the percent difference indicating that the fluid is comprised of at least a first fluid type.