TROUBLESHOOTING SYSTEM AND TROUBLESHOOTING METHOD OF NOX SENSOR

摘要

PROBLEM TO BE SOLVED: To diagnose more accurately whether failure, in which responsiveness of the output value degrades, is occurring, in a NOx sensor provided downstream side of a NOx selective reduction catalyst in an exhaust passage of an internal combustion engine.;SOLUTION: When reducing agent adsorption capability of a NOx selective reduction catalyst degrades to a predetermined level or below, supply of reducing agent to the NOx selective reduction catalyst is stopped (S102), and it is diagnosed whether or not responsiveness of an NOx sensor failure is occurring based on change in output values of the NOx sensor at downstream side after that (S103 to S105).;COPYRIGHT: (C)2010,JPO&INPIT