Exhaust from a diesel engine can be harmful to the environment and human health. So, to make the exhaust cleaner, manufacturers started adding an aftertreatment system to their trucks in 2007. This includes a Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF).
![](https://cdn-ds.com/blogs-media/sites/669/2017/12/28094246/FSX-Booth-lineup_wider-DPF-1038x375.jpg)