WHAT IS A DOC?
A diesel oxidation catalyst, or DOC, is a device that utilizes a chemical process in order to break down the pollutants from a diesel engine in the exhaust stream, turning them into less harmful components, similar to a gas engine's catalytic converter.

Diesel oxidation catalysts are normally honeycomb-shaped configurations coated in a catalyst designed to trigger a chemical reaction to reduce gaseous emissions and PM. 

​Diesel oxidation catalyst typically reduce emissions of the particle matter by 20% to 40% or more and gaseous emissions by 50% to 70%.