Some of the most popular performance upgrades available for diesel engines are EGR and DPF deletes. While removing exhaust components from your vehicle may seem counter-intuitive, having a delete done brings with it many benefits.

Deletes are aftermarket kits that remove factory-installed components that limit performance and fuel economy in diesel engines. The most common delete kits are EGR deletes, DPF deletes, and DEF deletes.

What is a Diesel Delete?

Diesel exhaust is notoriously dirty and oily soot and carbon buildup from the exhaust will eventually clog up the EGR (exhaust gas recirculation) valve, EGR sensors, EGR cooler, and DPF (diesel particulate filter). As these components plug up, performance and fuel economy will drop meaning that these emissions-related parts will have to be cleaned or replaced. Some diesel owners are opting to “delete” these pollution-control components instead.

A diesel delete involves taking out the DEF system, removing the catalytic converter and DPF, and installing a new exhaust. The vehicle’s ECU (engine control unit) will also have to be reprogrammed using a tuner. This tuner will replace the OEM (original equipment manufacturer) software with a new program that controls the fuel delivery and engine timing.

The tuner will also recalibrate the OBD (onboard diagnostic system) to properly monitor engine operating parameters and ensure that no emissions-related codes pop up because of the missing components.

After a diesel delete is completed, the soot-clogging issues are eliminated. There may also be performance improvements such as an increase in torque/horsepower as well as an improvement in fuel economy. These positive changes can depend on the tuner, the after-market software, and the engine hardware.

There are three types of kits available when it comes to performing a diesel delete: DPF, DEF, and EGR. These diesel engine services are popular among diesel owners.

What are DPF, DEF and EGR Delete?

DPF Delete

Diesel Particulate Filters (short for DPF) and Exhaust Gas Recirculation systems (short for EGR) are both designed to limit harmful emissions. While they perform an important function, they can limit the performance and power of your engine, especially if they are malfunctioning or clogged up with particulates from your engine.

For example, DPFs remove harmful particulates from your exhaust gases with little to no downside until they start to clog up. A blocked or obstructed DPF will restrict airflow, making it harder for your engine to function and even causing engine failure in extreme cases unless you take the time to clean your DPF regularly.

If your DPF becomes damaged, it can be quite expensive to repair. Plus, removing the particulate matter can affect your vehicle’s power, fuel economy, and engine life. Over time, an existing DPF system will create poor fuel economy. Once removed, fuel economy can improve by up to 30%.

Because many diesel owners use their trucks for towing or carrying heavy loads, increased performance and power are a priority. For this reason, many diesel truck owners opt to have a DPF delete done on their vehicles.

DEF Delete

The DEF (diesel engine fluid) system operates similarly to the DPF, removing soot from your engine and storing it in a canister within your exhaust system. Just like the DPF, the system will clear out excess soot by going into a regen cycle and using your vehicle’s fuel to burn off and blow out the soot. The DEF can also reduce performance and fuel efficiency but can also cause issues with the system freezing up. DEF is mostly made of water so, when you live in a colder climate, you run the risk of having your fuel freeze within the DEF system.

This DEF delete bypasses or removes the SCR system, which is intended to use DEF (Diesel Exhaust Fluid) to reduce nitrogen oxide emissions from diesel exhaust. Doing this reduces maintenance but also increases emissions and violates environmental laws in many jurisdictions at the state and federal levels.

EGR Delete

Similarly, EGR works to reduce the number of nitrogen oxides (NOx) in your exhaust and lower your engine temperature by diverting a small amount of exhaust gas into the exhaust manifold. Adding exhaust gas (which is no longer combustible) to the engine works to dilute the air in the combustion chambers, lowering the power and temperature of the combustion, reducing your engine power.

While it limits the amount of exhaust released into the atmosphere, it also increases the amount of soot in your engine and reduces performance and fuel economy. EGR systems can also cause engine troubles such as cracked parts and other expensive issues. It can also create other issues such as sticky valves, leaky cylinders, cracked engine components, and coolant problems.

The side effects of reduced engine power and performance have caused many motorists to consider getting rid of these parts entirely – a procedure is known as DPF and EGR delete.

What are the pros and cons of DPF and EGR Removal ?

Removing your DPF and EGR can improve your car’s power, performance, and fuel efficiency. Since DPFs and EGRs effectively reduce engine performance by obstructing your exhaust and diluting the fuel/air mix in your combustion chambers, removing them may result in:

  • Improved performance

    Removing these systems can increase horsepower and torque, improve throttle response, and make the drive smoother.

  • Better fuel economy

    By eliminating restrictive emissions systems, diesel engines can operate more efficiently and use less fuel.

  • Reduced maintenance costs
    DPF, DEF, and EGR systems require regular maintenance and can be prone to issues like clogging and component failures. Removing them can help avoid costly repairs.

  • Longer engine life
    Removing emissions systems can reduce strain on engine components and help prevent premature wear and tear.
  • Reduced engine temperatures Removing these systems can help decrease engine temperatures.

However, there are also some potential drawbacks to consider:

  • Voided warranty: Deleting the DPF or EGR can void your vehicle's warranty.
  • Emissions standards: Without the DPF, your car will no longer meet emissions standards, which could result in fines in some states.
  • Risk of motoring law violations: Removing the DPF or EGR can increase your risk of being charged with motoring law violations. 

Is EGR, DEF, and DPF Delete Legal?

An emissions delete involves removing or modifying emissions-reducing parts from a vehicle's exhaust system, such as the EGR, DPF, DEF, and more, to improve performance. Though they may improve performance, diesel deletes should be illegal in many countries because they modify regulated parts of the exhaust system, increasing harmful pollutants in the air.

Is a Diesel Delete Right For You?

If you own a diesel vehicle and are interested in avoiding engine troubles while improving your performance, a diesel delete may be the solution. However, as mentioned already, some countries like USA state and federal laws underscore significant risks to implementing deletes, including fines and federal prosecution. We can't provide legal advice on this matter, but we encourage you to follow all Environmental Protection Agency and Department of Motor Vehicle guidelines regarding emission equipment standards.