Method for checking SCR catalysts in exhaust gas system of internal combustion engine of motor car, involves altering size of ammonia sensor to output signal to ammonium cross-sensitive sensor, which is attenuated below threshold level

摘要

The method involves detecting operability of an ammonia sensor (43) and an ammonium cross-sensitive sensor (44), which is arranged between two SCR catalysts (13, 21). Size of an internal combustion engine (6) is alternated after-treatment of an exhaust gas system. Nitrogen oxide concentration of exhaust gas is determined. Ammonium storage capacity of the first SCR catalyst is recognized. Size of the ammonia sensor is altered to output signal to the ammonium cross-sensitive sensor, which is attenuated below threshold level. Independent claims are also included for the following: (1) a computer program comprising a set of instruction for detecting catalyst (2) a computer program product has a set of instruction for detecting catalyst.