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Cummins ISX EGR Delete: CM870 vs CM2250/CM2350 Explained
October 19, 2026

Cummins ISX EGR Delete: CM870 vs CM2250/CM2350 Explained

If you operate a Class 8 truck powered by a Cummins ISX15, choosing the right EGR delete kit starts with identifying the engine generation. Although the CM870 (2002–2007) and the CM2250/CM2350 (2010–present) share the same 15-liter platform, their EGR system layouts, cooler designs, and connection points differ. As a result, their kits are not interchangeable.

One common fitment mistake is choosing a kit based on the truck’s model year rather than the engine’s control module generation. This guide breaks down the key differences between the CM870 and CM2250/CM2350 EGR systems, explains how Stage 2 kits differ from basic block-off plates, and shows you what to check before ordering.

What Separates the CM870 from the CM2250 & CM2350?

The biggest difference is the emissions system design. The CM870, used from 2002 to 2007, belongs to an earlier ISX generation in which EGR played a central role in emissions control. The later CM2250 (2010–2012) and CM2350 (2013 onward) operate within a more complex emissions system that combines EGR with diesel particulate filtration (DPF) and selective catalytic reduction (SCR).

These differences affect more than the model year. The generations use different EGR plumbing, cooler arrangements, and port configurations, so a kit designed for the CM870 should not be assumed to fit a CM2250 or CM2350. The CM2250 and CM2350 kits may share compatible sealing hardware, but fitment should still be confirmed against the specific engine configuration and the manufacturer’s application details.

If you’re unsure which generation your truck has, check the engine data plate and serial number rather than relying on the truck’s model year alone. This is especially important for trucks built around generation-change years, when the same model year may correspond to different engine configurations.

Use the identification guide below to narrow down your engine generation before comparing kits or placing an order.

Engine Years EGR System
CM870 2002–2007 First-generation EGR
CM2250 2010–2012 EGR + DPF + SCR
CM2350 2013+ Updated EGR + emissions system

What Goes Wrong on the ISX EGR System?

Although the CM870 and CM2250/CM2350 use different EGR layouts, two common concerns are EGR valve problems and cooler failure.

The first is the EGR valve. Over time, carbon and soot deposits can build up and interfere with valve movement. If the valve sticks open, exhaust gas may continue entering the intake when it shouldn’t, affecting airflow, engine performance, and drivability. The exact symptoms depend on the engine generation and the nature of the fault.

The second concern is the EGR cooler. This heat exchanger uses engine coolant to reduce exhaust gas temperatures before the gas is routed back into the intake. Repeated heat cycles and internal wear can eventually damage the cooler, potentially allowing coolant to leak into the exhaust or intake path.

One warning sign is unexplained coolant loss without an obvious external leak. Depending on the severity of the failure, a leaking cooler may also contribute to abnormal operating temperatures or engine derate conditions. Because coolant entering the intake or cylinders can cause serious damage, unexplained coolant loss deserves prompt diagnosis rather than guesswork.

For a working Class 8 truck, these problems can mean unexpected downtime, repair expenses, and lost operating hours. Identifying the underlying fault early helps operators make better maintenance decisions.

How Long Does the ISX EGR Cooler Last?

There is no single mileage figure that predicts when an ISX EGR cooler will fail. Its service life depends on factors such as operating conditions, coolant condition, maintenance history, and repeated exposure to high temperatures.

Poor coolant condition can contribute to corrosion, while demanding workloads expose the cooler to repeated thermal cycling. Some coolers may remain serviceable for a long time, while others develop problems earlier. Rather than relying on mileage alone, watch for warning signs such as unexplained coolant loss and have the cooling system inspected to identify the actual source.

If the cooler is suspected of leaking internally, confirm the diagnosis before deciding on a repair. Other cooling-system faults can produce similar symptoms, so replacing components without proper inspection may not solve the problem.

Stage 1 vs. Stage 2: Why Does It Matter?

The main difference between Stage 1 and Stage 2 kits is the number of EGR-related openings they are designed to seal. A Stage 1 kit typically focuses on the main EGR valve mounting port, while a Stage 2 kit may include additional plates and plugs for the exhaust crossover connection, coolant passages, and other openings, depending on the engine generation and kit design.

Those extra sealing points matter because CM870 and CM2250/CM2350 engines use different EGR layouts. The correct kit should account for the relevant ports and connections rather than simply cover the main valve opening.

Before choosing a Stage 2 kit, check the included hardware and application details for your specific engine. The goal is to understand what each kit contains and which engine configuration it is designed for, instead of assuming that every Stage 2 kit seals the same openings.

What gets sealed Stage 1 Stage 2
Main EGR valve port Covered Covered
Exhaust crossover tube Left open Sealed
Coolant feed and return passages Left open Sealed
Secondary EGR circuit openings Left open Sealed

The extra sealing matters because any passage left open after the EGR hardware comes out is a place where exhaust can leak, coolant can seep, or contamination can get in. Closing all of them is what keeps the engine bay clean and removes the leftover leak paths.

What’s Actually in Each Kit?

CM2250/CM2350 Stage 2 EGR Delete Kit (2010–Present)

The ISX15 CM2250/CM2350 Stage 2 EGR Delete Kit is designed for 2010–Present ISX15 engines and provides a complete solution for sealing the factory EGR system after component removal. Unlike a simple block-off plate, this ISX15 EGR Delete Kit uses precision-machined plates and plugs to close multiple EGR-related ports and passages, helping ensure the exhaust, intake, and coolant-side openings are properly addressed.

Built for heavy-duty diesel applications, this CM2250 CM2350 EGR Delete Kit features durable metal sealing components and OEM-style mounting points for a cleaner installation. The kit is engineered specifically around the later ISX15 EGR layout, providing a better fitment solution than trying to adapt an earlier CM870 EGR delete kit to a newer engine platform.

For 2010-Present Stage 2 ISX 15 CM2250 CM2350 EGR Delete Kit

CM870 Stage 2 EGR Delete Kit (2002–2007)

Engineered specifically for 2002–2007 first-generation ISX engines without DPF/SCR systems, the ISX CM870 Stage 2 EGR Kit provides a complete, heavy-duty solution tailored to the engine’s unique EGR layout.

Unlike basic Stage 1 plates that only block the main valve, this precision CNC-machined Stage 2 kit includes anodized plates, expansion plugs, threaded fittings, and high-temp O-rings to completely seal the EGR valve, crossover tube, and coolant lines. Designed for a direct bolt-on OEM fit, it prevents internal coolant leaks, intake contamination, and performance derates to ensure maximum uptime.

Seguler For 2002-2007 ISX CM870 Stage 2 EGR Delete Plug Kit Stage 1 Plates and Plugs

Both options deliver a full Stage 2 sealing solution. The difference comes down strictly to the emissions era and port layout they are machined for. Matching the hardware to your specific engine generation—rather than the truck’s model year—is what guarantees a exact bolt-on fit and long-term reliability.

CM870 vs CM2250 vs CM2350: How Do They Compare?

CM870 CM2250 CM2350
Years 2002–2007 2010–2012 2013+
Emissions era EGR only EGR + DPF + SCR EGR + DPF + SCR
Kit it takes CM870 kit CM2250/CM2350 kit CM2250/CM2350 kit
Calibration Custom required Custom required Custom required

Three engine generations, two kit options. The CM870 uses a distinct EGR layout, while the CM2250 and CM2350 are covered by a shared kit designed for their applications. The CM871 (2007–2010) has a different EGR configuration and is not covered by either kit discussed here. Before ordering, always verify your engine code and confirm fitment with the official product specifications rather than relying on the truck’s model year alone.

Which Kit Fits Your Engine?

Choosing the correct kit starts with identifying your engine generation, not just your truck’s model year.

For example, a 2010 Peterbilt may have a late CM871 or an early CM2250, depending on its original configuration. Check the engine data plate for the engine model and serial number before ordering.

Once you’ve confirmed the engine code, use the following guide: the CM870 (2002–2007) requires the CM870-specific kit, while the CM2250 and CM2350 use the shared kit designed for those applications. The CM871 is not covered by either kit discussed here because it uses a different EGR layout.

Always verify the exact engine configuration against the official product fitment details before placing your order.

If your engine is… Use this kit
CM870 (2002–2007) CM870 Stage 2 kit
CM2250 (2010–2012) CM2250/CM2350 Stage 2 kit
CM2350 (2013+) CM2250/CM2350 Stage 2 kit
CM871 (2007–2010) Different layout — confirm before ordering

Which Trucks Does Each Kit Cover?

Cummins ISX engines are used across a wide range of Class 8 trucks, including models from Volvo, Peterbilt, Mack, International, Freightliner, and Kenworth. However, compatibility depends on the specific engine generation, not just the truck brand or model year.

The CM870 kit is intended for compatible 2002–2007 ISX CM870 applications, while the CM2250/CM2350 kit covers specified 2010-and-later ISX15 engines from those truck manufacturers. Exact fitment can vary by engine configuration, so the listed year ranges should be treated as a starting point rather than the only deciding factor.

Two trucks from the same manufacturer and model year may require different kits if they use different ISX generations. Before ordering, check the engine data plate and confirm the engine code against the official product fitment details to help avoid choosing an incompatible kit.

Does an ISX EGR Delete Need a Tune?

Depending on the ECM calibration and engine configuration, changes to the EGR system can trigger fault codes or engine derate conditions. Calibration requirements should be confirmed before installation, as they can vary between ISX generations and individual ECM setups.

Physical hardware changes alone may not resolve the diagnostic issues associated with the factory EGR system. If calibration changes are needed, work with a qualified diesel tuning specialist who can confirm compatibility with your specific engine and ECM.

The tuning process can also differ by generation. Some CM2250 applications support calibration through an OBD-II interface, while certain CM2350 ECMs may require additional unlocking procedures before they can be reprogrammed. These requirements depend on the specific ECM and its software configuration, so verify the process with your tuner before beginning the installation.

How Involved Is the Installation?

The installation primarily involves mechanical work rather than electrical modifications. The process involves removing the relevant factory EGR components and fitting the kit’s plates and plugs to the designated openings. The CNC-machined components are designed for a bolt-on fit, helping reduce the need for custom fabrication. Properly cleaning the mating surfaces and positioning the supplied sealing components are important parts of the job.

Access is often the more challenging part. On a Class 8 truck, reaching the EGR valve, cooler, and associated plumbing may require removing surrounding components, depending on the engine configuration and available clearance. Although standard hand tools may cover much of the work, the overall time depends on the truck’s setup, component condition, and installer experience. A complete installation can be a substantial job rather than a quick afternoon repair.

Before starting, confirm any applicable calibration requirements with a qualified diesel technician. The necessary steps can vary by ECM generation and configuration, so plan for both the mechanical work and any required diagnostic or calibration procedures in advance.

Is an ISX EGR Delete Legal?

For trucks certified for on-highway use in the United States, removing or disabling required EGR emissions controls can violate the federal Clean Air Act’s anti-tampering provisions. These rules prohibit tampering with required emissions systems or disabling their intended function.

Labeling a truck or kit “off-road” or “competition use only” does not automatically make the modification legal. The vehicle’s intended use and applicable federal and state regulations determine whether the modification is permitted.

Commercial truck operators should also consider potential inspection, compliance, and financial risks. Before modifying an ISX engine, confirm the requirements that apply to your vehicle and operating location. Compliance should be verified before any emissions-related changes are made.

Common ISX EGR Delete Mistakes to Avoid

Ordering by truck year instead of engine code

A truck’s model year alone may not identify its ISX generation. Some 2010 trucks, for example, may have a late CM871 or an early CM2250. Check the engine data plate before ordering.

Confusing CM870 and CM871 

Despite their similar names, these engines have different EGR layouts. Their kits are not interchangeable, so confirm the engine code and product fitment before purchasing.

Assuming all Stage 2 kits cover the same ports

Stage 2 configurations can vary by engine generation and kit design. Review the included plates, plugs, and sealing components to confirm they match the intended application.

Overlooking calibration requirements

Physical EGR system changes may trigger fault codes or derate conditions, depending on the ECM and engine configuration. Confirm the applicable calibration requirements before installation.

Choosing by truck brand alone

The same truck manufacturer may use different ISX generations across model years. Match the kit to the actual engine code rather than relying on the truck badge.

Why Choose Seguler for Your ISX EGR Delete?

Choosing the right Cummins ISX EGR Delete Kit starts with matching the hardware to the engine generation. Seguler offers dedicated Stage 2 EGR Delete Kits for CM870 and CM2250/CM2350 applications, with components designed around the respective EGR layouts.

The two kit options address different engine configurations, so choosing the correct version is essential. Before ordering, review the product specifications, included hardware, and fitment details for your engine.

Whether you operate an ISX CM870 or an ISX15 CM2250/CM2350, confirming the engine code is the most important step toward selecting the appropriate kit. Use the official product details to verify compatibility before making your purchase.

Learn more about Seguler’s Cummins ISX Stage 2 EGR Delete Kits: seguler.com

Legal Disclaimer: Removing or disabling emissions equipment is illegal for on-highway use in the United States under the Clean Air Act. These parts are intended for off-road, competition, and closed-course use only. Labeling a vehicle or part “off-road” or “competition use only” does not by itself create a legal exemption, and aftermarket parts alone do not automatically void a warranty under the Magnuson-Moss Warranty Act — but a modification that causes a failure may not be covered. Check all federal, state, and local regulations before making any change to your truck.

Frequently Asked Questions

Q:What’s the difference between Stage 1 and Stage 2?

A: A Stage 1 kit blocks only the main EGR valve mounting port. A Stage 2 kit adds plates and plugs for the exhaust crossover connection, the coolant feed and return passages, and any secondary EGR circuit openings — the difference between plugging one hole and sealing the whole system. 

Q:Are the CM2250 and CM2350 kits interchangeable?

A: Yes. Cummins kept the flange patterns and EGR cooler mounting points nearly identical between the two generations, so the standard block-off and sealing hardware — the plates, threaded plugs, and gaskets — carries across both.

Q:Are the CM870 and CM871 kits interchangeable?

A: No. The CM870 and CM871 were designed with fundamentally different EGR system layouts and port configurations, and mixing them up leaves you with components that don’t fit. Check the engine data plate and confirm CM870 before ordering.

Q:Do I need a tune for the EGR delete?

A: Depending on the ECM calibration and engine configuration, blocking EGR flow can trigger fault codes or derate conditions. A compatible calibration is typically required after physical EGR changes.

Q:How do I know which engine I have?

A: Check the engine data plate for the engine code and serial number. The truck’s model year is a guide, not a definitive answer — a 2010 truck can be either a late CM871 or an early CM2250. 

Q:Which trucks does each kit fit?

A: The CM870 kit is listed for 2002–2007 trucks running the ISX CM870, and the CM2250/CM2350 kit covers 2010-and-later trucks running the ISX15 CM2250 or CM2350 — across the Volvo, Peterbilt, Mack, International, Freightliner, and Kenworth models that used those engines.

Q:What happens if I order the wrong kit?

A: The plates and plugs won’t line up with the ports they’re supposed to seal, because the CM870 and the CM2250/CM2350 route their EGR plumbing differently. You’ll end up with components that don’t seat — and an engine that still has open passages. Confirming the engine code first avoids the whole problem.

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