An incorrect calibration setting in the Engine Control Module (ECM) software may cause miscalculation of sulfur oxide (SOx) levels captured within the Lean NOx Trap (LNT) component of the exhaust’s Diesel Particulate Filter (DPF). This miscalculation could, with extended operation under certain driving conditions, affect the purge process applied to remove SOx particles from the DPF-LNT. In this condition, the capacity of the DPF-LNT may become saturated and, as a result, the nitrogen oxide (NOx) emissions from the vehicle could exceed the permitted level.