| 摘要 |
The method is applied when one or more specific enabling conditions 20 of a selective catalytic reduction (SCR) system are satisfied. The specific enabling conditions may be NOx engine out quantity, SCR upstream temperature, or an increasing trend in diesel exhaust fluid (DEF) dosing request (500, figure 3). The method comprises cyclically determining the quantity of DEF requested «Xt over a predetermined time interval by integration and comparing 21 with a first threshold KX until the integrated DEF request quantity is greater than the first threshold. When the integrated DEF request quantity is greater than the first threshold, the method also comprises calculating 22 a second threshold KY based upon a catalyst reagent load (510, figure 4) over the same time interval, and comparing 23 the second threshold with an integrated reagent catalyst load «Yt over the same time interval. An undesired reagent dosing is detected 25 when the integrated reagent catalyst load is less than or equal to the second threshold. The first threshold may be a function of the enabling conditions. |
