Many common Cummins ISX engine problems are related to the emissions control system. We’ve identified fixes for turbo and regen problems — plus, a word of caution on DPF delete problems. We have what you need to know about Cummins ISX engines and engine alternatives too.

In This Article

What to Know Before Buying a Cummins ISX

Cummins is known for building heavy-duty diesel engines for everything from pickup trucks and tractor-trailers to farm equipment and heavy machinery. If you’re thinking of ordering something with a Cummins ISX engine, here are few things to know:

First, Cummins recommends major engine overhaul around the 500,000-mile mark. These engines can be incredibly reliable if they are properly maintained. That means understanding the needs of the DPF system (more on that later), doing scheduled maintenance on time, and performing other preventative measures like oil changes and replacing injectors, as needed.

There’s also a service online called Cummins QuickServe, which is a library of information on Cummins engines and equipment. If you need parts or service information, you can probably find it there.

In addition, there are some well-known problems with Cummins ISX engines. We have the details below.

Common Cummins ISX Engine Problems

In past 10 years, as the government began regulating diesel emissions more strictly, Cummins ISX engines have started to have issues with emissions systems and/or mechanical components.

In general, if your engine won’t start, there’s probably an issue with the control electronics. However, if your engine turns over but doesn’t run properly, makes unusual noises, and/or is having fuel consumption issues, the problem is likely mechanical. Here are three common Cummins ISX mechanical issues:

Cummins ISX Turbo Problems

Most of the problems around the ISX turbo are due to its variable-geometry design, meaning that the compressor blades in the turbo can change their angle of attack for more or less pressure — as required by the engine. With this added complexity comes an increase in maintenance issues.

The actuator that controls the turbo is controlled by the Engine Control Module (ECM), so it’s worth checking to see if it’s an electronics problem first. But, if the problems go beyond the ECM or actuator, and you need to replace the ISX turbo, it is possible to replace it with a less complicated turbo. Swapping the turbo for a new one isn’t too difficult, and, since it’s common to go more than 300,000 miles before issues crop up, you shouldn’t have to make the change too early or often in the life of the engine.

Another Cummins ISX turbo problem is lack of boost, which is often accompanied by high engine temperatures. This points to a problem with the EGR valve. Replacing the EGR valve, as well as cleaning the turbo hot side (or possibly replacing it), should resolve the issue. It also helps to get your engine regularly checked and maintained.

Cummins ISX Regen Problems

The diesel particulate filter (DPF) needs to be cleaned regularly through a process known as a diesel regen or regeneration. This is another complicated emissions control system intended to improve air quality. A common problem in ISX engines is the DPF not regenerating. Idling issues are the leading cause of problems with the emissions control systems in these engines; often, trucks that are driven and then let to sit in idle can’t regenerate properly. Cummins ISX regen problems can often be solved (or prevented) by simply shutting off the engine when you’re not driving. The engine should automatically regenerate when properly used.

Cummins ISX DPF Delete Problems

While it is possible to remove the DPF system and other parts of the emissions control system, this isn’t recommended — and it may even be illegal, depending on where you live. For example, in 2005, New York City passed strict rules for diesel engines operated within city limits. If you operate a vehicle in an area where DPF systems are installed or where it’s illegal to modify an emissions control system, you may face hefty fines for violations. Make sure to review all applicable laws in your area of operation before you make a change.

Additionally, removing or modifying other parts of a vehicle’s emissions system (like the EGR system, for example, or the catalytic converter on a gasoline engine) is often a federal crime and can carry a stiff penalty. Removing the EGR system on a diesel like a Cummins ISX can result in fines up to $10,000.

Cummins ISX Engine Alternatives

Since there are many known Cummins ISX engine problems — especially with the complicated emissions control system — you may be wondering about alternatives. A few of Cummins’ top competitors are Caterpillar, GM, Detroit, and International. But, keep in mind, these companies are bound by the same Environmental Protection Agency requirements, so they may have similar issues.

When buying a truck or a piece of heavy machinery, the manufacturer will provide engine options, if any are available. If a Cummins engine is your only factory option but you’d like something else, a custom engine swap is a pricey alternative. These Cummins ISX problems are most commonly identified on 2010, 2011, and 2013 model years.

In Summary

Those are the Cummins ISX problems be be aware of. Cummins is a well-known manufacturer of diesel engines for long-haul trucking, manufacturing, and other heavy-duty uses. Some of the most common ISX engine problems are related to the emissions control system. These systems have grown increasingly complicated as diesel emissions have become more strictly regulated. However, with proper care and maintenance, these engines should be able to work hard for a long time.

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