Car Maintenance 101: How Does An Aftertreatment System Work?

Purchasing a diesel car is an appealing option due to factors like greater mileage, energy efficiency, and longer lifespan, to name a few.

However, learning how to maintain it is a continuous process. You need to be knowledgeable about how to handle the vehicle’s other critical components, such as the aftertreatment system, in addition to changing its tires or batteries.  

Due to limited information about aftertreatment systems on the web, many vehicle owners are left in the dark. In this article, you’ll learn what an aftertreatment system is, why understanding it is important, and some other essential information about aftertreatment systems that every owner of a diesel-powered car owner should be aware of.  

What Is An Aftertreatment System?  

Decades of automotive innovation have led to greener emissions, which is due to a vehicle’s aftertreatment system. An aftertreatment system is an assembly of devices responsible for reducing the harmful emissions released by your car engine. 


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In order to function, your car needs to burn diesel fuel, which produces harmful byproducts such as carbon monoxide, nitrogen oxides (NOx), carbon dioxide, and methane—collectively referred to as greenhouse gases (GHGs). An aftertreatment system targets specific molecules from these chemicals and converts them into less hazardous substances. In the United States, all diesel engine owners must equip their vehicles with an aftertreatment system that meets emission regulations.  

Diesel-powered vehicles are significantly more expensive than gasoline-powered ones. Dealing with aftertreatment system care is crucial to maintaining its stellar performance, so make sure to browse educational info about taking care of your aftertreatment system.  

A Breakdown Of The Aftertreatment System  

To learn how your vehicle’s aftertreatment system works, it’s essential to dissect its components. Upon looking at your exhaust, you’ll find an array of technology that manages combustion gases as they exit the engine, such as the following:  

  1. Exhaust Gas Recirculation (EGR): The main function of an EGR system is temperature regulation. When cooled exhaust gas is sent back into the combustion changer, the EGR ensures the chamber temperature drops, thus reducing the production of NOx.  
  2. Diesel Oxidation Catalyst (DOC): While the EGR deals with NOx reduction, particulate matter (PM) emissions, the black soot exiting your car’s exhaust pipes increase during the process. The DOC system deals with this problem.  

The DOC is a filter made of precious metals that serves as the first stage of the aftertreatment funnel. In addition to oxidizing PM, the DOC burns carbon monoxide hydrocarbons and unburned oil to produce less harmful carbon dioxide and water.  

  1. Diesel Particulate Filter (DPF): The next system, the diesel particulate filter (DPF), takes care of any soot that the DOC fails to oxidize. Its primary role is to lessen particulate count to up to 90% when they exit your vehicle’s pipes. Since DPF traps soot generated by your car, regular DPF cleaning is necessary.  
  2. Selective Catalytic Reduction (SCR): Last but not least, the SCR is a more advanced technology that lessens NOx emissions by using a catalyst like ammonia to produce diatomic nitrogen or nitrogen and water. The SCR contains a diesel exhaust fluid (DEF) known as AdBlueⓇ, made from deionized water and urea, which is essential for the SCR’s function and overall maintenance of the aftertreatment system.  

Why Do You Need To Learn About The Aftertreatment System?  

Diesel-powered vehicle owners should be familiar with a car’s aftertreatment system, especially those who operate commercial fleets. Although the professionals handle maintenance and repairs, having comprehensive knowledge and training on how your aftertreatment system works is the first step to building a maintenance program. The filters found in the aftertreatment system, like the DPF and DEF filters, need routine maintenance in accordance with the guidelines set by the original equipment manufacturer (OEM).  



After all, taking the initiative to learn about an aftertreatment system shows that you value the environment by ensuring that your car generates cleaner emissions. Most importantly, business owners with diesel-generated vehicles should strive to learn about their aftertreatment systems for proper fleet management, as their practices can create environmental impacts. 

Some Tips For Maintaining Your Aftertreatment System  

For maximum reliability and performance of the aftertreatment system, drivers and fleet owners should follow these tips:  

  • When performing routine inspections and maintenance, follow the OEM’s recommended guidelines.  
  • Focus on components with scheduled maintenance intervals, like the hydrocarbon injector, DPF filter, tank filler neck filter, and DEF pump. 
  • Make sure that your engine runs with appropriate oil and fuel.  
  • For repairs and replacements, use high-quality, genuine parts only.

The Bottom Line  

An aftertreatment system may seem intimidating to maintain, but knowing the technologies involved in this system and consulting manufacturer resources can make your learning process much easier. If you’re planning to use diesel-powered vehicles for your business, prioritize your aftertreatment system to get the most out of your cars.  

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