Method and system for detecting fault of rear oxygen sensor

Abstract

A method for detecting a fault of a rear oxygen sensor installed on an exhaust pipe of a vehicle may include determining whether the rear oxygen sensor satisfies a diagnosis entry condition, comparing an output voltage of the rear oxygen sensor to a preset fault determination voltage range so as to determine whether the output voltage of the rear oxygen sensor is included in the fault determination voltage range, changing the duty of a heater of the rear oxygen sensor when the output voltage of the rear oxygen sensor is not included in the fault determination voltage range, determining whether the output voltage of the rear oxygen sensor, controlled by changing the heater duty, is included in the fault determination voltage range, and confirming that the rear oxygen sensor has a fault, when the output voltage of the rear oxygen sensor is included in the fault determination voltage range.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority to Korean Patent Application No. 10-2014-0099170, filed on Aug. 1, 2014, the entire disclosure of which is hereby incorporated by reference herein.BACKGROUND[0002]1. Field of the Disclosure[0003]The present disclosure relates to a method and system for detecting a fault of a rear oxygen sensor which is installed on an exhaust pipe of a vehicle; and, particularly, to a method and system for detecting a fault of a rear oxygen sensor which monitors an output voltage of the rear oxygen sensor in a state where power of a heater to activate the rear oxygen sensor is cut off for a predetermined time, and detect a fault of the rear oxygen sensor.[0004]2. Description of Related Art[0005]In general, a vehicle measures the concentration of oxygen contained in exhaust gas discharged from an engine using an oxygen sensor, and determines the state of the exhaust gas. Then, the vehicle controls combustion to reduce exhaus...

AI Technical Summary

Benefits of technology

[0028]The heater power controller may decrease the duty of the power applied to the heater to a minimum for a preset time.

[0029]The heater power controller may decrease the duty of the power applied to the heater for a time in which the rear oxygen sensor maintains an activation temperature.

Problems solved by technology

However, the load pulse method has a problem in that the load pulse method cannot continuously monitor a fault of the rear oxygen sensor and cannot consider the state of the engine.

Thus, the load pulse method cannot deal with various regulations in which the state of the engine must be considered.

Furthermore, the voltage bias method has a problem in that the voltage bias method may determine whether the rear oxygen sensor is opened according to a driver's driving habit, even though the voltage bias method can continuously monitor the rear oxygen sensor when the rear oxygen sensor is activated.

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