What is a Deleted Diesel Truck? (and why you shouldn't do it)

Updated on Feb 2, 2024

If you’ve spent much time in or around the diesel truck community, you’ve likely heard the term ‘deleted’ directed toward modern pickups. Before 2008, three-quarter-ton and up heavy-duty diesel pickups (2500+) had extremely lax emissions requirements, allowing millions of metric tons of pollutants to enter the atmosphere annually.

However, this all changed when the EPA required all 2008 model year and up diesel pickups to ship from the factory with an EGR (exhaust gas recirculation) system, DPF (diesel particulate filter), and NOx (diesel nitrogen oxide) filter, significantly cleaning up tailpipe emissions. No longer would Diesel pickups spout black soot from their tailpipes or force surrounding drivers to roll up their windows to avoid noxious fumes. At least, that was the EPA’s plan.

The diesel community is a rather resourceful bunch; within months of the EPA’s new regulations, companies began manufacturing emissions defeat devices, allowing diesel pickup owners to remove the exhaust filter components and deactivate the EGR systems. Around this time, the slang terms ‘delete’ and ‘deleted diesel’ came about, referencing the removal of post-2008 diesel pickup emissions systems.

In this guide, we’re tackling the topic of deleted diesel pickups, including why diesel owners choose to delete emissions, emission system components, and our justifications for leaving your truck’s emissions system intact. If you’ve debated deleting your diesel, read on!

Why Delete a Diesel Pickup?

So, what’s the purpose of deleting these emissions systems in the first place? In most cases, 2008+ diesel pickups make fairly more power than their pre-emissions counterparts and burn cleaner, so what’s the upside?

Countless reliability issues arose in the initial years of implementing the diesel emissions system. Diesel pickups are intended to be worked, and worked hard; this means countless hours spent towing and hauling over long distances. If these conditions are met, the engine will run for long periods and stay hot, which results in few reliability qualms. Doing so burns excessive carbon from the intake/cylinder head and allows plenty of time to regenerate, which involves injecting extra fuel into the cylinders and changing engine parameters to increase exhaust temps, which ignites and burns excessive carbon from the filters.

However, not every diesel pickup owner works their truck regularly. Some merely tow a travel trailer every few months but ultimately rely on their pickup for daily driving most other days. Unfortunately, stop-and-go conditions and short distances traveled don’t allow the engine to reach proper operating temperatures or the exhaust to regenerate, thus leading to clogged DPF filters, EGR faults, and other issues. And when it comes time to replace these components outside the factory warranty, owners are hit with massive service bills!

Aside from reliability, early emissions systems also significantly limited power and efficiency. DPF and NOx filters formed massive restrictions in the exhaust, thus reducing exhaust flow and the engine's intake of fresh air. These restrictions also minimized exhaust and turbo sounds, which most diesel drivers had grown fond of.

Deleting these early emissions systems had several benefits, including fewer points of failure and, better reliability, improved power, and significantly improved fuel economy; what’s not to love?

Fortunately, as technology improved and manufacturers implemented DEF (diesel exhaust fluid) systems in most diesels around 2010, the reliability of diesel emission systems improved drastically. Additionally, efficiency went through the roof. Take the 2024 RAM 3500 High Output, for instance, which packs a 6.7L Cummins inline 6-cylinder engine capable of an astounding 420 horsepower and 1,025 lb-ft of torque from the factory! With enough power to pull down a house, the Cummins-powered RAM still earns a respectable 16–21 MPG.

How to Delete a Diesel Truck

So, how does one delete a diesel pickup, anyway?

Deleting a diesel pickup involves removing all emissions system components, including the DPF filter, NOx filter, DEF system, and EGR system. Then, a tuner or programmer with delete-capable tuning electronically deactivates the associated systems, preventing the truck’s computer from recognizing an issue, throwing error codes, going into limp mode, or not running altogether!

Emissions System Components

Now that we know the names of emissions components, it's time to learn what each does and how it's removed! Let’s take a look at each component's contributions to emissions control.

Catalytic Converter

Like gasoline-powered cars, diesel pickups feature a catalytic converter. This component operates similarly to catalytic converters on gasoline-powered vehicles, though it typically contains less-valuable catalysts. Diesel catalytic converters merely break down unburnt fuel and carbon monoxide into less-harmful byproducts, like carbon dioxide and nitrogen. For more information, check out our article on preventing catalytic converter theft!

Removing a diesel catalytic converter marginally improves exhaust flow by reducing restriction, though it allows unburnt fuel and harmful gasses to escape the exhaust.

DPF Filter

The DPF filter, or diesel particulate filter, is a diesel-specific emissions component. This exhaust filter is a form of after-treatment that captures soot, ash, and other contaminants. Once the DPF reaches capacity, the ECM initiates a ‘regen cycle’ in which additional fuel dumps into the cylinders, and specific engine parameters force the engine to run at higher temperatures. These conditions ignite the excess fuel, which burns the carbon out of the DPF.

Removing the DPF, like the catalytic converter, eliminates restrictions in the exhaust. It also removes a failure point, preventing clogging from short drives and low-RPM driving conditions. However, removing this component also allows excessive soot and ash, often referred to as ‘rolling coal.’

NOx Filter

The NOx (nitrogen oxide) filter is another inline exhaust filter used to convert harmful compounds, like nitrogen oxides, into less-harmful byproducts.

Like the catalytic converter and DPF filters, removing the NOx filter may reduce exhaust restrictions, though it allows harmful gasses to exit the exhaust system.

DEF System

DEF (diesel exhaust fluid) systems are part of the updated SCR (selective catalytic reduction) system, which replaced the standalone NOx filter in 2010. The SCR system improves the effectiveness of emissions filtration by injecting a urea-based liquid into the exhaust upstream of the NOx catalyst. The urea vaporizes, which mitigates NOx production, ensuring a clean, efficient burn.

Removing the DEF system eliminates the need to routinely purchase and refill DEF fluid; however, it also significantly increases tailpipe emissions.

EGR System

Lastly, we have the EGR system, or exhaust gas recirculation system. This system captures and recirculates small, metered amounts of unfiltered, high-soot exhaust gasses into the intake and back through the engine, allowing unburnt fuel another chance to combust. This process increases engine efficiency, reduces fuel consumption, and lowers NOx emissions.

Unfortunately, the EGR system is also dirty, especially on a diesel pickup. As soot mixes with oil vapor, the EGR system produces sludge, which coats valves, grid heaters, turbochargers, and other components. It can also contaminate the engine oil, reducing its lubricity and, thus, increasing engine wear. For these reasons, it’s a common component to delete; however, doing so significantly increases NOx concentration in exhaust gasses.

Why Leave Your Diesel’s Emissions System Intact?

Now, this article may seem like an advocacy for deleting a diesel pickup rather than a deterrent, but don’t be mistaken! At RealTruck, we don’t condone deleting your diesel emissions systems; we rebuke it! In this section, we’re covering the countless downsides of deleting a diesel pickup that significantly outweighs any benefits.

Voiding Your Truck’s Factory Warranty

When you purchase a new or gently used vehicle, warranty coverage is one of the most significant drawing factors. Forget paying for costly repairs out of pocket; just take it to the dealership! Unfortunately for deleted truck owners, most repairs will likely be denied if the emissions system is tampered with, especially drivetrain issues.

Keep your diesel pickup’s emissions system intact to save yourself from headaches and expensive repair bills.

Expensive Initial Cost

While several diesel truck owners hope to minimize maintenance and repair costs by deleting emissions systems, it’ll take years of savings to offset the initial cost of delete-capable tuning, exhaust components, and the labor to install said parts. In most cases, you’ll never see any actual savings, so why bother?

Legal Issues

Deleting a diesel isn’t just ill-advised; it’s a federal crime. Tampering with a vehicle’s emission system is a direct violation of federal law, even if you live in a state or county without annual or biannual emissions testing. If you’re caught driving a deleted diesel truck, you could face fines of up to $5,000 per non-emissions part! If you own a business selling/installing emissions defeat devices, those fines can increase to seven figures!

Increased Tailpipe Emissions

All other negatives aside, deleting a diesel truck affects the air we breathe. Decades of work and research have gone into the emissions systems on every vehicle, transforming harmful and carcinogenic compounds into harmless elements, and doing away with these systems undoes all of that work. If not for yourself, keep your pickup’s emission systems intact for your fellow citizens and future generations.

Alternatives to Deleting Your Diesel Pickup

As aforementioned, recent advancements in emissions technology have virtually eliminated all issues with early emissions-compliant diesel pickups, like poor fuel efficiency, reliability, and power production. For this reason, paired with the negatives listed above, we’d recommend avoiding emissions deletes. Instead, consider emissions-compliant performance upgrades!

Components like DPF-back exhaust systems, air intakes, and emissions-compliant tuners offer significant power gains while retaining your pickup’s factory emissions system; plus, you’ll retain your truck’s factory warranty and avoid costly legal expenses.

As always, contact our experts for any additional questions or product inquiries!