A FAULT DIAGNOSIS METHOD OF SCR SYSTEM AND AN APPARATUS THEREOF

摘要

The present invention relates to a fault diagnosis method of an SCR system and a fault diagnosis apparatus. According to an exemplary embodiment of the present invention, the fault diagnosis method of an SCR system comprises: a detection step (S100) of detecting one or more operation states of a lean nox trap or a state of a urea tank; a determination step (S200) of determining whether the state of the lean-nox trap or the state of the urea tank detected from the detection step (S100) satisfies a corresponding condition to block monitoring of purification efficiency of the SCR system; and a blocking step (S300) of blocking the monitoring of purification efficiency of the SCR system when the determination step (S200) determines that the state of the lean-nox trap or the state of the urea tank satisfies the corresponding condition to block the monitoring of purification efficiency of the SCR system. According to the present invention, incorrect detection of a faulty SCR system can be prevented as the diagnosis of the SCR purification efficiency is blocked when the state of the lean-nox trap is a regeneration state (DeNox), the urea tank is in the frozen state, and the urea tank has a cavity.