Selective catalytic reduction catalyst managing method for exhaust gas post-treatment device of motor vehicle, involves comparing measured quantity of water at exhaust path with theoretical quantity of water in downstream of catalyst

摘要

The method involves measuring quantity of water at an exhaust path (11) based on moisture content measured by a hygrometry sensor (4) arranged in downstream of a selective catalytic reduction catalyst (1). Theoretical quantity of water in downstream of the catalyst is calculated based on a theoretical quantity of water added by an injector (6) in the exhaust path. The measured water quantity is compared with the calculated theoretical water quantity. Failure of the injector is diagnosed if a difference between the measured and calculated water quantities is greater than a predefined threshold. An independent claim is also included for an exhaust gas post-treatment device of a motor vehicle, comprising a hygrometry sensor.