Cummins Emission Solutions is a division that makes aftertreatment systems for diesel engines

Cummins Emission Solutions (CES) is a business unit of Cummins Inc. that designs and manufactures the equipment that sits between your diesel engine's exhaust and the tailpipe. This equipment—called aftertreatment systems—removes harmful pollutants from exhaust gases before they leave your vehicle. If you own a diesel truck, bus, or industrial equipment, you are almost certainly running a CES system or one very similar to it.

The reason this matters to you is straightforward: these systems are complex, they fail, and when they do, your vehicle will not pass inspection and you cannot legally drive it. Understanding what CES systems do and how they work helps you recognize problems early, understand repair costs, and make decisions about maintenance that actually prevent breakdowns.

Key Takeaways

  • Cummins Emission Solutions makes the equipment that cleans diesel exhaust, including selective catalytic reduction (SCR) systems and diesel particulate filters (DPF).
  • These systems are required by law on all modern diesel engines and must function for your vehicle to pass emissions inspection.
  • Common failures include DPF clogs, SCR catalyst degradation, and sensor faults, each with different warning signs and repair costs.
  • Preventive maintenance—using the correct fuel, changing oil on schedule, and avoiding excessive idling—extends the life of these systems significantly.
  • Repair or replacement of CES components is expensive but necessary; driving with a failed system risks fines and inspection failure.

How Cummins Emission Solutions systems clean your exhaust

Modern diesel engines produce two main pollutants that regulations require you to remove: particulate matter (soot) and nitrogen oxides (NOx). Cummins Emission Solutions builds two primary systems to handle these.

The diesel particulate filter (DPF) traps soot particles in a ceramic or metal substrate. As you drive, soot accumulates in the filter. When the filter reaches a certain load, your engine's computer triggers a regeneration cycle—the engine burns off the trapped soot at high temperature, turning it to ash. This happens automatically during normal driving, though sometimes it requires a longer highway drive at steady throttle to complete. If regeneration fails repeatedly, the filter clogs and your vehicle loses power, fuel economy drops, and you get a warning light.

The selective catalytic reduction (SCR) system injects a urea-based fluid called diesel exhaust fluid (DEF) into the hot exhaust stream. A chemical reaction converts NOx into harmless nitrogen and water. The SCR catalyst—another CES component—speeds up this reaction. If your DEF tank runs dry, the SCR shuts down and your engine will not start or will go into limp mode. If the catalyst degrades, NOx passes through and your vehicle fails inspection.

Why your vehicle needs these systems and what happens if they fail

Federal and state emissions standards require every diesel vehicle sold since 2007 (for heavy trucks) and 2009 (for light-duty trucks) to have a working DPF and SCR system. These are not optional add-ons—they are part of the engine's design. Your vehicle's computer monitors both systems constantly and will illuminate a warning light if either one fails.

If your DPF fails, you lose engine power, fuel economy worsens, and you cannot pass inspection. Driving on a clogged DPF can damage the engine itself because exhaust backpressure rises. If your SCR fails, your vehicle enters a derate mode where engine power is cut to 5 mph or less, making the vehicle undriveable. You will not be able to legally operate the vehicle until the system is repaired.

Repair costs vary widely. A DPF cleaning can cost $300 to $800 if caught early. A full DPF replacement runs $1,500 to $3,500 depending on the engine size and vehicle type. SCR catalyst replacement is typically $2,000 to $4,000. These are not small expenses, which is why understanding what causes failure matters.

Common reasons CES systems fail and how to recognize them

DPF clogs happen when regeneration does not complete. This occurs most often in vehicles that spend a lot of time idling or in stop-and-go city driving where exhaust temperatures never get hot enough to burn off soot. Long-haul highway driving actually keeps DPF systems healthy because sustained high temperatures trigger regeneration. If you see a yellow or amber warning light shaped like an engine or a filter, or if your vehicle loses power suddenly, your DPF may be clogged.

SCR failures usually stem from DEF running out. DEF is consumed during normal operation—a typical truck uses about one gallon of DEF for every 50 gallons of diesel fuel. If you ignore the DEF low warning and let the tank empty, the engine will not restart. DEF can also crystallize in cold weather if the heater element fails, blocking the injection nozzle. Sensor faults—where the computer detects a problem with the DEF quality, temperature, or flow—also trigger SCR shutdowns.

Contaminated fuel or poor-quality oil accelerates failure of both systems. Fuel with high sulfur content clogs the DPF faster. Oil that is not changed on schedule leaves deposits that damage the SCR catalyst. Using the wrong oil viscosity or skipping oil changes by thousands of miles is one of the most common ways owners damage these expensive systems.

Preventive maintenance that actually extends CES system life

The single most effective thing you can do is follow your vehicle manufacturer's oil change interval exactly. CES systems are sensitive to oil quality and condition. Use only the oil grade and type specified in your owner's manual—usually a low-ash diesel oil. High-ash oils leave deposits in the SCR catalyst and shorten its life significantly.

Buy diesel fuel from reputable stations. Fuel with high sulfur content or contamination clogs the DPF faster and damages the SCR catalyst. If you run a vehicle on biodiesel blends, confirm that your engine and CES system are rated for that fuel—not all are.

Avoid excessive idling. Idling does not generate enough exhaust heat to trigger DPF regeneration, so soot accumulates. If you must idle for extended periods, periodically rev the engine or take a short highway drive to allow regeneration to complete. Monitor your DEF level and refill before it runs empty—do not wait for a warning light. Keep the DEF tank clean and use DEF from sealed containers to prevent contamination.

Have your vehicle scanned with a diagnostic tool if a warning light appears. Early detection of a DPF clog or SCR fault can mean the difference between a $500 cleaning and a $3,000 replacement. Many shops offer DPF cleaning services that cost far less than replacement and can restore function if caught early.

What to expect when a CES system needs repair

If your vehicle enters limp mode or fails inspection, you will need to visit a diesel specialist or a dealership. A technician will connect a diagnostic scanner to read the fault codes from your engine computer. These codes tell exactly which component failed and why—whether it is a clogged DPF, a faulty SCR sensor, low DEF, or a degraded catalyst.

For a DPF clog, the shop may attempt a forced regeneration using the diagnostic tool, which heats the exhaust to burn off soot. This works if the filter is not too far gone and costs $300 to $600. If the filter is severely clogged or damaged, it must be replaced. Some shops offer DPF cleaning services where the filter is removed and cleaned in a specialized oven, then reinstalled—this costs $400 to $1,000 and is cheaper than replacement but not always possible if the filter is cracked.

For SCR failures, the repair depends on the fault code. If DEF is low, you straightforward refill it. If a sensor failed, the sensor is replaced ($200 to $600). If the catalyst is degraded, it must be replaced ($2,000 to $4,000). Some shops can test the catalyst to confirm it is truly failed before you commit to replacement.

Understanding the difference between CES systems and other aftertreatment brands

Cummins Emission Solutions is one of the largest manufacturers of diesel aftertreatment systems, but not the only one. Other major brands include Bosch, Delphi, and Tenneco. However, if your vehicle is powered by a Cummins diesel engine—which is common in Ram, Ford, and Dodge trucks, as well as many industrial and commercial applications—your aftertreatment system is almost certainly a CES system.

The repair and maintenance principles are the same across all brands: keep oil clean, use quality fuel, monitor DEF levels, and address warning lights promptly. The specific components and sensor locations differ, but the underlying technology is similar. A diesel technician familiar with your vehicle's year and model will know which system you have and how to service it.

Frequently Asked Questions

Can I drive with a DPF warning light?

You can drive short distances, but you should not ignore it. A DPF warning means regeneration is not completing, and the filter is accumulating soot. Continuing to drive allows the filter to clog further, which can damage the engine and turn a $500 repair into a $3,000 one. Get it scanned within a few days.

What happens if my DEF tank runs completely empty?

Your engine will not start or will shut down when ready after starting. The vehicle enters a protective mode to prevent you from driving without SCR function. You must refill the DEF tank and have the system reset by a technician before the engine will run again.

Is DPF delete legal?

No. Removing or disabling a DPF is illegal under federal emissions law and state law in most places. Your vehicle will fail inspection, and you can face fines. Dealerships and reputable shops will not perform this work. Aftermarket delete kits void your warranty and expose you to legal liability.

How often should I have my CES system inspected?

If your vehicle is running normally with no warning lights, a formal inspection is not necessary beyond what happens during routine maintenance. However, if you tow heavy loads, idle frequently, or drive mostly in city traffic, have a technician check your DPF and SCR system during your annual inspection or every 50,000 miles.

Can a clogged DPF cause engine damage?

Yes. A severely clogged DPF raises exhaust backpressure, which can damage engine seals, gaskets, and internal components over time. This is why addressing a DPF warning light quickly is important—waiting weeks or months can turn an expensive repair into a catastrophic engine failure.