Cummins ISX Problems: Fixes for Turbo, Regen Issues, & More

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.

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. Heavy-duty diesel engines should have their piston liners, bearings, and piston rings replaced at 500,000 miles, as well as service of the injection system and any other necessary improvements.

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.

Note that heavy-duty engines including Cummins are subject to federal regulation by the Environmental Protection Agency (EPA). Several rules to keep in mind include:

  • Diesel engines may fall under the category of heavy-duty onroad engines or under the nonroad emissions standards depending on their horsepower. However, some form of engine standards from the EPA apply to all model years of heavy-duty engine after 1970.
  • In addition to considering your engine’s horsepower, you should follow the standards that were current in the year that your engine was built. For example, engines built since 2014 with over 751 horsepower — including Cummins’ high horsepower family — are subject to Tier 4 Final nonroad rules. High horsepower engines built between 2010 and 2013 fall under Tier 4 Interim nonroad rules. Meanwhile, Cummins ISX engines typically have between 300 and 650 horsepower and are subject to heavy-duty onroad regulations.
  • Manufacturers certify new engines and vehicles before selling them. As an engine owner, your compliance with EPA standards largely involves carrying out regular maintenance and avoiding engine tampering. It is illegal for you to disable any of the emission controls after purchasing a certified engine — meaning you can’t legally remove the engine’s diesel particulate filter (DPF), exhaust gas recirculation (EGR), or selective catalytic reduction (SCR) systems.

You can find more information about emissions standards, including the full rule summaries, at the Environmental Protection Agency’s website.

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.

If your engine won’t start, there are many potential causes; there may be an issue with the control electronics, or your ignition may be disabled after a fault has been detected by the computer’s safety system. Dirty air filters, bad fuel, or a host of other cuases could be at fault if your engine turns over but doesn’t run properly, makes unusual noises, and/or is having fuel consumption issues; however, the problem may also be 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 comes with challenges, including reprogramming the computer system. It can also impact the engine’s efficiency and performance. However, 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 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, or switching the truck to high idle if it is running while parked, so it runs at a temperature high enough to cut down on clogging. The engine should automatically regenerate when properly maintained, but will still need occasional manual regeneration, as the DPF gets dirty over time even with automatic regen.

Cummins ISX DPF Delete Problems

While it is possible to remove the DPF system and other parts of the emissions control system, this is illegal in the U.S. due to the EPA’s emission standards, as detailed above. Removing any pollution-control element from your engine is in violation of the EPA’s onroad and nonroad engine regulations. If you tamper with your engine and then operate your vehicle in an area where it’s illegal to modify an emissions control system, you may face hefty fines or criminal penalties for violations. Make sure to review all applicable laws in your area of operation before you make a change.

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 Detroit, International, and Paccar. 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 to 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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