A control device of an internal combustion engine is configured to perform a fuel cut-off control and an abnormality diagnosis control. A heating device for heating an element of an air-fuel ratio sensor is controlled by making an element temperature of the air-fuel ratio sensor become a target element temperature. The target element temperature of the air-fuel ratio sensor during a high temperature control period from a time when a prescribed high temperature control begins after a start of the internal combustion engine to a time when the prescribed high temperature control is completed after completion of the abnormality diagnosis control of the air-fuel ratio sensor is set to be higher than the target element temperature outside the high temperature control period.

An apparatus includes a processing circuit structured to receive a first signal indicative of an upstream air-fuel equivalence ratio from a first sensor positioned upstream of an intake of a catalyst, receive a second signal indicative of a downstream air-fuel equivalence ratio from a second sensor positioned downstream of the intake of the catalyst, determine an actual oxygen storage capacity of the catalyst based at least in part on the received first signal and the received second signal, compare the actual oxygen storage capacity to a maximum storage capacity, and provide a fault signal in response to the actual oxygen storage capacity exceeding the maximum storage capacity. The apparatus also includes a notification circuit structured to provide a notification indicating that the second sensor is faulty in response to receiving the fault signal.

A driving mode setting part sets a driving mode when a vehicle travels by automatic driving. An item setting part sets a prioritized diagnosis. A storage part stores plural diagnosis conditions provided in correspondence to each diagnosis item. A target setting part sets a control target value. A motive power source part controls a motive power source based on the control target value. Each diagnosis item is assigned to the driving mode, for which the diagnosis condition is most easily satisfied. The item setting part sets, as a prioritized item, the diagnosis item assigned to the set driving mode. When the prioritized item is set, the target setting part sets the control target value so that the motive power source attains a state, which is close to the diagnosis condition of the prioritized item.

Methods and systems are provided for determining a type of spark plug fouling. In one example, a method may include differentiating spark plug fouling due to soot accumulation from spark plug fouling due to fuel additive accumulation based on a current on a control wire of the spark plug following application of a dwell command. Further, exhaust oxygen sensor degradation and/or exhaust catalyst degradation may be determined based on switching frequencies of one or more exhaust oxygen sensors and the type of spark plug fouling.

The control system of an internal combustion engine performs normal operation control including lean control for making the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst a lean air-fuel ratio, and rich control for making the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst a rich air-fuel ratio. The normal operation control includes judgment reference decreasing control decreasing the judgment reference storage amount in the lean control when during the time period of performing the lean control, the air-fuel ratio of the exhaust gas flowing out from the exhaust purification catalyst becomes the lean judged air-fuel ratio or more. The control system judges that the exhaust purification catalyst is abnormal when the judgment reference storage amount becomes less than a deterioration judgment value.

An oxygen sensor diagnosis control system of a hybrid electric vehicle is provided. The system of a hybrid electric vehicle eliminates an uncertainty of the number of diagnoses of an oxygen sensor and restrains diagnoses of the oxygen sensor in a hybrid electric vehicle. The system of a hybrid electric vehicle includes a hybrid controller operates a vehicle, and determines conversion of an oxygen sensor diagnosis mode based on a result obtained by calculating an oxygen sensor diagnosis index. Additionally, the controller determines whether a condition for diagnosing an oxygen sensor is satisfied when the oxygen sensor diagnosis index decreases to initiate a diagnosis inducing mode or a compulsory diagnosis mode.

An internal combustion engine comprises an exhaust purification catalyst arranged in an exhaust passage of the internal combustion engine and being able to store oxygen in inflowing exhaust gas and an air-fuel ratio sensor arranged at a downstream side of the exhaust purification catalyst in a direction of exhaust flow and detecting an air-fuel ratio of exhaust gas flowing out from the exhaust purification catalyst and stops or decreases a feed of fuel to a combustion chamber as fuel cut control. The abnormality diagnosis system calculates a characteristic of change of an air-fuel ratio based on an output air-fuel ratio output from the air-fuel ratio sensor at the time when the output air-fuel ratio first passes a part of an air-fuel ratio region of a stoichiometric air-fuel ratio or more after an end of the fuel cut control, and diagnoses abnormality of the air-fuel ratio sensor based on the characteristic of change of the air-fuel ratio. As a result, the diagnosis system can diagnose the abnormality of deterioration of response of the downstream side air-fuel ratio sensor when necessary without fail when performing fuel cut control.

A diagnosis apparatus of a fuel supply system includes an operation state detector, an air-fuel ratio sensor, a fuel injection amount calculator, a threshold value table, an abnormality information acquiring device, and an abnormality determining device. In the threshold value table, operation ranges of an internal combustion engine are provided based on an engine speed and a throttle opening. In the threshold value table, a lean side threshold value and a rich side threshold value of an air-fuel ratio correction factor to determine abnormality of the fuel supply system are set beforehand for each of the operation ranges. The abnormality information acquiring device is configured to determine whether the air-fuel ratio correction factor has exceeded the lean side threshold value or the rich side threshold value extracted from the threshold value table according to an operation state so as to acquire abnormality information.

To provide a sensor control device capable of identifying a short circuit terminal with a simple configuration and whose identification operation is not easily affected by environmental conditions around the sensor. The sensor control device includes a short circuit detection unit that detects a short circuit of a sensor having a plurality of terminals, a resistance value control unit that increases a resistance value of an element between the terminals when the short circuit of the sensor is detected by the short circuit detection unit, and a short circuit terminal identification unit that identifies at which of the plurality of terminals a short circuit occurs when the resistance value control unit increases the resistance value of the element between the terminals to a set value or greater.

An evaluation and control unit, designed as an ASIC, for operating a broadband lambda sensor that includes at least one electrical line. The evaluation and control unit includes at least one electrical terminal for electrically connecting to the electrical line of the broadband lambda sensor, and a device for determining a setpoint value of a current flowing into the electrical terminal and for comparing this setpoint value with the current actually flowing into the electrical terminal and for comparing with the aid of comparators the electrical potential being applied to the electrical terminal with predefined limits.