Methods of monitoring replacement of a diesel particulate filter (DPF) by a non-particulate matter filter. The disclosed methods takes into account a change in delta pressure based soot load estimates (DPSLE) over time to detect whether the DPF has been replaced. The estimate, which is measured by the delta pressure drop across the filter, can be used to determine whether a device that does not have the capability of trapping soot, such as a muffler, has been inserted.