What is a DPF and Where is it Located?

Diesel engines power everything from semi trucks and pickups to commuter cars. Known for excellent fuel efficiency and torque output, diesel engines differ in a few distinct ways from their gasoline counterparts. Besides the most obvious and known differences (i.e different fuel and lack of spark plugs) the exhaust systems on modern diesel engines are incredibly complicated, utilizing a range of components not found on gasoline vehicles. One of these parts is known as the DPF, or diesel particulate filter. In this article, we are going to discuss the function of the DPF, where it’s located, and go over some important maintenance information. 

How Does Diesel Exhaust Work?

While diesels have been touted as clean and efficient engines, they are far from clean by default. When you think of diesel, it might bring to mind an image of plumes of black smoke coming out of the exhaust stacks of a semi-truck or the tailpipe of a big diesel pickup. 

Everything that makes a diesel engine “clean” happens after the combustion process in the exhaust system. Modern diesels employ several technologies to clean up the exhaust before it enters the atmosphere including exhaust gas recirculation (EGR), diesel exhaust fluid injection (DEF), and the aforementioned diesel particulate filter (DPF). 

Where is the DPF Located and How Does it Work?

The DPF typically sits after the exhaust manifold, before the DEF system. The purpose of the DPF is to capture any particulate matter that comes as a byproduct of diesel combustion. This matter is called soot. The DPF captures as much as 90% of the solid particles in the exhaust.

DPF Regeneration

Like any filter, the DPF will function less effectively as soot builds up over thousands of miles of driving. The soot contents of the filter can build up enough to impact fuel economy and engine performance. Luckily, a system called regeneration, often shortened to “regen”, helps reduce suit buildup and extend filter life. 

DPF regen involves literally burning the accumulated soot in the filter, leaving behind ash. There are three types of regen cycles on most diesel-powered vehicles. 

Passive DPF Regen

Passive regen occurs while you drive. When the exhaust temperature gets high enough, it will begin to burn off the soot captured by the DPF. Since the exhaust needs to reach and sustain high temperatures, passive regeneration requires longer drive times to effectively clean the DPF. Passive regeneration when you drive at a speed of at least 40 mph for more than 15 minutes

Active DPF Regen

Unlike passive regen, active DPF regeneration is a process triggered by the vehicle’s ECU. Additional fuel is sent through the exhaust system, allowing for the soot to combust and burn off to ash. Active regen is seen on diesel vehicles that drive shorter distances since these vehicles don’t drive long enough for passive regeneration to work. 

Forced DPF Regen

If your DPF is severely clogged with soot, your repair shop may recommend a process known as a forced DPF regen. When the filter becomes severely clogged, the vehicle can enter “limp home mode” which limits engine power and speed. Forced regeneration is initiated with a diagnostic tool and is done when the vehicle is stationary.

Maintaining Your DPF

Diesel particulate filters are an essential emissions control component in your exhaust system, and can be very expensive to replace. To get the most life our of the filter, it’s important to allow your vehicle to complete the regeneration process. 

Driving Habits

If you typically drive short distances, you should make a habit of taking your diesel vehicle out for a longer cruise every so often. This will allow for active regeneration to take effect, keeping the soot levels in the DPF at a manageable level. 

Those who put a lot of highway miles on their vehicle will reap all the benefits of passive regeneration, keeping your filter operating at its best for longer. 

DPF Cleaning

While the regeneration reduces soot buildup in the DPF, the byproduct of this process ash, which is captured and stored in the filter. The ash needs to be periodically removed in order to prevent clogging. A DPF cleaning takes care of this, emptying out ash buildup, and providing more space to burn off soot deposits. 

DPF Replacement

In cases of severe buildup, the DPF may need to be replaced. Staying on top of maintenance and practicing good driving habits will prolong the life of the filter. These filters can be extremely expensive and are required on modern diesel engines. 

Symptoms of DPF Problems

A clogged DPF is far and away the most common issue diesel owners will run into with this component. Here are some common things to look out for:

• Check Engine Light
• Low engine power
• Reduced Fuel Economy
• DPF light on dashboard
• Limp home mode
• Odor from the exhaust 

DPF Services at Red Rock Repair Las Vegas

If you own a diesel vehicle, it’s essential to stay on top of maintenance. DPF and other emissions control equipment require servicing in order to function properly, and preventative maintenance will help reduce downtime and prolong the life of your vehicle. 

Red Rock Repair is Summerlin’s premier auto repair shop. Our expert technicians have years of experience servicing diesel vehicles and will help you keep your running like it should. Whether you drive a diesel pickup or a Volkswagen TDI, we’ve got you covered. Give us a call to schedule an appointment today!