The invention relates to the technical field of
diesel engine aftertreatment
system control, and particularly discloses a method for diagnosing abnormal concentration of a
urea solution of an SCR
system. The method comprises the steps that whether an enabling condition is met or not is detected; when the enabling condition is met, integral operation is carried out on upstream and downstream
NOx sensor measurement values of the SCR
system, and meanwhile integral operation is carried out on an
NOx value calculated by an SCR
chemical reaction model; according to the result of integral operation on the upstream
NOx sensor measurement value of the SCR system, whether the accumulated value of the SCR upstream NOx
mass flow exceeds a preset threshold value or not and whether the accumulated timeexceeds preset time or not are judged; if the accumulated value of the SCR upstream NOx
mass flow exceeds the preset threshold value and the accumulated time exceeds the preset time, the difference value between the accumulated value of the SCR upstream NOx sensor
mass flow and the accumulated value of the mass flow calculated by the SCR
chemical reaction model is calculated; and according to whether the difference value exceeds a preset difference value or not, whether the concentration of the
urea solution of the SCR system is abnormal or not is judged. According to the method for diagnosingabnormal concentration of the
urea solution of the SCR system, diagnosis of abnormal concentration of the urea solution can be achieved.