An engine ECU is provided with an abnormality-diagnosis unit performing an abnormality diagnosis of an Air-Con ECU, and a monitoring IC monitoring the abnormality-diagnosis unit. The abnormality-diagnosis unit determines whether the output signal of the Air-Con ECU is normal based on the specified criterion value, so that the abnormality diagnosis of the Air-Con ECU is performed. The monitoring IC determines whether a criterion value is normal, which is used during the abnormality diagnosis of the Air-Con ECU. The abnormality-diagnosis unit performs an abnormality diagnosis of the monitoring IC. When the monitoring IC determines that the criterion value is abnormal or the abnormality-diagnosis unit determines that the monitoring IC is abnormal, the abnormality diagnosis of the Air-Con ECU is prohibited and a specified operation for abnormality is performed.

The present invention relates to a method (100) for cold start optimization of an internal combustion engine (10) comprising: determining (110) a start of an engine preheating device (12); transmitting (115) a selected coolant temperature T.sub.cool.sub._.sub.trans to an engine control unit (14); and adapting (140) the selected coolant temperature T.sub.cool.sub._.sub.trans transmitted to the engine control unit (14) to a current coolant temperature T.sub.coll.sub._.sub.current during a time interval t following the start of the internal combustion engine (10). The present invention further relates to an auxiliary control unit (22) which is configured to execute the method (100).

Methods and systems are provided for rationalizing a hydrocarbon sensor in a hybrid vehicle, the hydrocarbon sensor used for feed-forward air/fuel ratio control during fuel vapor canister purging events. In one example, a method comprises routing blow-by gasses from a crankcase of an engine of the vehicle to an intake manifold of the engine and then to a fuel vapor storage canister, and indicating whether the hydrocarbon sensor is functioning as desired based on a magnitude of a response of the hydrocarbon sensor during the routing. In this way, the hydrocarbon sensor may be diagnosed under conditions when the canister is substantially free from fuel vapors, and where engine run-time is limited.

A short-circuit pinpointing device for testing a wide-range air/fuel sensor includes a current-sink and a controller. The current-sink is selectively connectable to one or more of sensor-terminals of a wide-range air/fuel sensor that include a reference-terminal, a pump-terminal, a return-terminal, and a tag-terminal. The controller is in communication with the current-sink and the sensor-terminals. The controller controls the connection of the current-sink to the one or more sensor-terminals. The controller also determines one or more status-values based on signals present at the sensor-terminals. The controller also determines a sensor-status of the wide-range air/fuel sensor based on the connection of the current-sink and the one or more status-values.

Methods and systems are provided for determining engine knock sensor degradation. In one example, a method may include sending an excitation signal to an actuator to generate vibrations in the absence of engine combustion, and determining engine knock sensor degradation by comparing the knock sensor output with the excitation signal.

A method is disclosed for detecting a malfunction of an oxygen sensor in the exhaust gas system of an internal combustion engine having several cylinders. The cylinders are operated at the same air-fuel ratio and the resultant first output signal of the oxygen sensor is monitored. The cylinders are operated at varying air-fuel ratios and the resultant second output signal of the oxygen sensor is monitored. The first and second output signals are compared to determine whether the oxygen sensor has malfunctioned.

A wiring line abnormality detecting device is configured to be provided in a sensor signal detection device that includes a detection unit for detecting a sensor signal through a plurality of wiring lines connected to a sensor, and includes a potential detection unit that detects each of potentials of the plurality of wiring lines, a potential difference detection circuit that detects a potential difference between the plurality of wiring lines according to each of the potentials of the plurality of wiring lines detected by the potential detection unit, and a determination circuit that specifies a failure wiring line with a high-voltage power supply short circuit among the plurality of wiring lines according to the potential difference detected by the potential difference detection unit.

Methods and systems are provided for enabling a transfer function of a direct injector and a port injector, each fueling an engine cylinder, to be accurately learned. During selected conditions, the direct injected fuel fraction may be actively changed from a target fraction to one of an upper and lower limit of the direct injector so as to provide a measurable air-fuel ratio error. Fueling errors for the distinct fuel injectors is then learned based on the measured air-fuel ratio error relative to the actively changed fuel fraction.

Methods and systems are provided for diagnosing temperature sensors of a vehicle. In one example, a method may include, at a duration after an engine-off event, determining that an intake air temperature measured by an intake air temperature sensor of the vehicle is less than an ambient air temperature measured by an ambient air temperature sensor of the vehicle. In response to the determining, the method may include flowing air from a catalyst across the intake air temperature sensor; and indicating the intake air temperature sensor is functional responsive to the intake air temperature converging to the ambient air temperature during the flowing.

Methods and systems are provided for diagnosing temperature sensors of a vehicle. In one example, a method may include, at a duration after an engine-off event, determining that an intake air temperature measured by an intake air temperature sensor of the vehicle is greater than an ambient air temperature measured by an ambient air temperature sensor of the vehicle. In response to the determining, the method may include flowing ambient air across the intake air temperature sensor, and indicating the ambient air temperature sensor is functional responsive to the intake air temperature converging to the ambient air temperature during the flowing.