Internal-combustion engine i.e. diesel engine, operating method for motor vehicle, involves determining characteristic of feed ratio and measuring signal, and determining operating condition of selective catalytic reduction system

摘要

The method involves determining a characteristic of a feed ratio of nitrogen oxides to a reducing agent. A characteristic of a measuring signal of an exhaust gas probe (38) is determined, where the probe is downstream to a selective catalytic reduction (SCR) catalyst (23) of a SCR system. An operating condition of the SCR system is determined based on gradients of both the characteristics. A temporal correlation of positive gradients of the characteristic of the measuring signal is detected by the SCR catalyst. An independent claim is also included for a device for operating an internal-combustion engine.