The Diesel Particulate Filter or DPF, is a ceramic filter that lives in the exhaust system. It is designed to remove diesel particulate matter or soot from the exhaust. DPF filters usually remove 85% to 100% depending upon efficiency. Most of the DPF’s today use a regenerative process to “clean” the filter. To do this, the exhaust gas must be raised high enough to burn off the particulate matter. This is usually done at highway speeds or the vehicle must pull over for 15-30 minutes to allow the regenerative cycle to run. If the filter is not cleaned on a regular basis, the vehicle could go into a “limp” mode, which is designed to keep the engine/exhaust system safe. At this point, only a dealer can fix the issue, which can be very expensive.