Six Signs That Your DPF Filter Is Clogged (& the Replacement Cost)

You may be familiar with the diesel particulate filters (DPF), but you might not know what they do. You may not know what the DPF is until your car has an inspection. How can you tell if your DPF has become clogged?

If the DPF filter becomes blocked or clogged the engine can suffer and an engine check engine light will appear on the dashboard. The DPF filter can cause increased fuel consumption or make the engine difficult to start. You may notice unusual smells and turbocharger problems.

We will discuss the symptoms and cost of replacing a blocked DPF filter. It is also discussed why replacing it is necessary and how expensive it can be. 

Bad/Clogged Diesel Particulate filter (DPF) symptoms

1. Verify Engine Light

A check engine light at the dashboard is usually an indication of a poor DPF. Diesel particulate filters use sensors to monitor temperature and pressure before and after filtering. If there is an error in the pressure, your engine control module will turn on the dashboard check engine light.

If you see a check engine light on your dashboard, you need to scan the trouble code memory with a code scanner to figure out what’s wrong.

2. Reduced engine performance

If the DPF gets blocked, it can cause severe damage to the exhaust system. This can cause a blockage in the ability to efficiently remove exhaust from the engine. 

When the backup is installed, your engine will feel weaker and more sluggish. As exhaust gases build up, it becomes harder to pump in new fuel. This can cause the engine not to be able accelerate as normal. The engine will also need more power in order to expel the extra gases. 

Related: Why is my car losing its power while accelerating? (Here’re the Causes)

3. Poor Fuel Efficiency

The engine will not work efficiently and you'll burn more fuel. Blockage of the filter causes inefficiency. This means that more fuel must be used to complete the same task. It’s also caused by the need for more fuel to get the desired results from your engine.

You will spend more on your fuel because of these issues. You will begin to see the price difference in diesel as it continues to climb. 

4. Problems Starting

Blockage of the DPF can cause exhaust gas buildup in your engine. This trapped gas isn’t able to go anywhere, creating more pressure than normal. This makes it difficult to turn the engine on. In fact, the engine won’t want to start unless that pressure gets released. 

The safety aspect of this problem is less important. Permanent damage to the engine could result from excessive pressure. This can lead to costly repairs. To save yourself this money, it’s best to clean the DPF before a blockage occurs. 

RELATED: Car Hesitates to Start – Causes & How to Fix

5. Strange Smells

Exhaust gas can build up and cause a distinct odor. This can be annoying and even dangerous.

Emission gases can cause respiratory problems and are dangerous to inhale. Additionally, while these smells are occurring, it’s difficult to tell if something else is wrong.

RELATED: 8 Car Odors & Smells You Shouldn’t Ignore 

6. Turbocharger Damage

If the exhaust system is blocked, it's important to also check the health and performance of the turbocharger. Temperatures can rise quickly if the flow of gas is impeded or slow down. When the problem isn’t resolved promptly, the turbine housing also gets hotter.

If the housing is not checked regularly, damage to turbochargers can occur. Leakage can happen and the turbocharger's efficiency may drop if it is not repaired. Carbonization can cause oil within the turbocharger's to become corroded, which could lead to motor damage. 

Diesel Particulate Filter Location

Diesel particulate filters (DPFs) are part of your vehicle's exhaust system. The filter is located ahead of the NOx trap (also known as the NOx storage catalyst converter). The DPF filter is often located close to the exhaust pipe.

It’s also found ahead of the exhaust pipe but will be found behind the first temperature sensor. You will need to remove the filters using a screwdriver. There may be O-rings, or other clamps that need to be removed after you have taken off the plates. 

Diesel Particulate Filter Function

Part of the exhaust system is the diesel particulate filter. It’s meant to trap particulate matter, such as ash and soot. A ceramic substrate is used to construct the DPF. This honeycomb structure traps debris and forms an effective honeycomb structure.

Soot is captured and stored by the diesel particulate filter, which allows for reduced emission. To help renew the DPF, this soot gets burned off occasionally. This regeneration takes place when excess soot is burned and deposits back into the filter. It reduces harmful emissions that you're used to seeing in diesel engines during acceleration. 

DPFs must be installed on every vehicle since 2007, according to EPA guidelines. This filter traps matter to ensure that the vehicle meets strict emission standards. 

Diesel Particulate Filter Replacement Cost

An all-new diesel particulate filters can run between $1,000 and $7,000. These new parts are never inexpensive, which is why it’s important to keep the system running properly. Most people opt to maintain the system rather than replace it. 

Considering that the DPF doesn’t normally fail in a low-mileage vehicle, it makes more sense to clean it. The cost to replace the DPF can be higher than the car's value. When properly maintained, the DPF shouldn’t need to be cleaned more than every 100,000 miles.

How to clean a diesel particulate filter

1. Thermal

You might be able to hear the thermal process if the DPF is taken to a professional cleaning company. This cleaning technique is also known as the “bake and blow.”

In an oven, the DPF is placed. As the temperature rises, soot is oxygenized and airflow moves the ash away from the filter. 

2. Aqua

The professional alternative has proven effective. Surfactant is used to surround the ash particles and make it easier for water on the substrate to remove them.

It must be completely dried after the substrate has been cleaned. You will need a special cabinet so it must be dried completely before you can reinstall the substrate. 

3. Cleaning Products for the Home

If you don’t want to take your vehicle to a professional for cleaning, you can try and do it yourself with a special additive. Some top brands are available for as low as $25 per bottle. These products help to reduce soot, ash and other harmful substances. 

Please follow all directions on the label. The engine should be running when you add it to the fuel tank. Once it has been added, it’s best to drive for thirty minutes. This allows the additive to circulate throughout the system. It doesn’t matter what speed you travel at, it will work. If it wasn't on, the DPF warning lamp might go out. 

Cleaning additives may be useful for clearing clogs. However, it is best to use them as maintenance. If you are using a cleaner every three to six months, you shouldn’t have any clogging issues down the road. 

You might want to try professional cleaning techniques if you still have problems after applying the additive. For more assistance, visit your diesel mechanic.