EGR systems are a standard part of modern diesel engines – but they are also one of the most common sources of frustration.
These systems are designed to reduce emissions and meet EPA regulations. However, they also introduce additional components that operate under high heat, pressure, and contamination.
Over time, this combination can lead to performance issues, costly repairs, and system failures.
Continue reading Problems with EGR Systems in Diesel EnginesDo you know why you need your EGR valve? It’s an important component of your EGR system that takes a ton of abuse because of its environment, and it’s gotten a bad reputation over the years. People often choose to delete it because of the problems it can cause your diesel engine and VGT turbo. But, did you know that this can end up costing you more money in the long run?
Continue reading Why is My Diesel Engine EGR Valve Failing?
Starting with model year 2027, the U.S. Environmental Protection Agency is implementing updated emissions standards for heavy-duty diesel engines as part of its Clean Trucks Plan.
These regulations focus on one primary goal:
👉 Reducing emissions while ensuring systems remain effective over a longer portion of the engine’s life.
For fleets, owner-operators, and anyone working with diesel engines, the changes are significant, but they are also structured around measurable standards.
This guide breaks down what is changing and how it applies to diesel engines in real-world operation.
Heavy-duty diesel engines are a major contributor to nitrogen oxide (NOx) emissions, which are linked to air quality concerns in urban and high-traffic areas.
The 2027 regulations are designed to:
These updates build on previous standards but introduce stricter limits and longer durability requirements.
One of the most significant updates is the new NOx limit:
👉 0.035 grams per horsepower-hour (g/hp-hr)
This represents an approximately 80%–90% reduction compared to current standards.
This change applies to heavy-duty engines used in:
The goal is to reduce emissions not just during testing—but across the full operating life of the engine.
Previous emissions standards focused heavily on highway driving conditions.
The 2027 regulations expand this by targeting:
These conditions are common in:
Engines will be required to maintain cleaner emissions performance even when they are not operating under steady highway load.
Another key change is how long emissions systems are expected to perform.
The EPA is extending the required useful life period, meaning:
These updated requirements are typically 1.5 to 2.5 times longer than previous standards.
This shifts the focus from short-term compliance to long-term durability.
To meet stricter emissions limits, engines will rely more heavily on aftertreatment systems.
These systems may include:
These technologies are designed to:
The 2027 regulations also update how engines respond to Diesel Exhaust Fluid (DEF) issues.
Previously, low DEF levels or system faults could trigger immediate power reduction (commonly referred to as “limp mode”).
Under the new rules:
This change is intended to maintain compliance while reducing sudden disruptions during operation.
From a design and operation standpoint, these changes will likely result in:
At the same time, engines will be designed to:
It’s important to note that the core function of diesel engines remains the same:
The primary changes are focused on emissions control and system longevity, not the fundamental operation of the engine itself.
The 2027 EPA diesel regulations introduce:
These updates are designed to ensure that emissions reductions are maintained throughout the life of the engine – not just when it’s new.
For fleets and operators, the impact will be seen in:
Understanding these changes now helps prepare for how diesel engines will be built and maintained moving forward.
As emissions systems continue to evolve, diagnosing and maintaining diesel engines becomes more system-focused.
If you’re working through:
Shop our website or call 844-304-7688 to speak with a diesel expert.
From diagnosis through delivery, we’re Highway and Heavy Parts.
You probably heard the stories about how much trouble EGR valves are for your diesel engine. And their history has indeed given them a bad reputation.
Continue reading Will An EGR System Delete Cause Diesel Engine Damage? (2025)Caterpillar built some of the most well-known diesel engines in the trucking industry.
From the early 3406 series to the C15, these engines earned a reputation for durability, rebuild-ability, and long service life.
But despite that reputation, Caterpillar exited the on-highway truck engine market in 2010.
So what actually happened?
Continue reading Why Caterpillar Stopped Making On-Highway Diesel Engines
