A SYSTEM AND A METHOD FOR DIAGNOSING THE PERFORMANCE OF TWO NOX SENSORS IN AN EXHAUST GAS PROCESSING CONFIGURATION COMPRISING TWO SCR UNITS

The invention relates to a method, system, and computer program product for diagnosing an exhaust gas processing configuration for a combustion engine of a vehicle, said configuration comprising two SCR-units, two NOx-sensors and two reducing agent dosing units suitably arranged, comprising the steps of: performing a series of reducing agent dosing operations by a first reducing agent dosing unit; comparing measured NOx-contents measured by a first NOx-sensor and a second NOx-sensor related to said operations; and if the respective NOx-content measured by the respective NOx-sensors during the performed reducing agent dosing operations are substantially equal, determining that the respective NOx-sensors provide a proper performance.