The difference between an active and passive diesel particulate filter is an active diesel particulate filter is a unit that provides its own heat, meaning that it’s hooked up to a 480-volt system. The elements inside the diesel particulate filter heat up, burn the hydrocarbons that come out of the engine, and collect all that into the DPF itself, the diesel particulate filter.
The passive diesel particulate filter is a unit that does not require an external source of heat. Usually, it’ll have a system within the engine itself that provides extra fuel to burn inside. The unit goes through a diesel oxidization catalyst that warms everything up, that heats it up, then it burns inside there, and it gets trapped in the filter.
There are some units that have a dosing device that’s attached to the exhaust as well, and that’ll dose fuel into the exhaust stream and be ignited by a sparkplug. Depending on the manufacturer’s recommendations, these filters can be different. There are some that you have to pull out and replace every 20 starts. There are some that you have to do annually. It just depends on the equipment manufacturer.