HomeCar NewsBlocked DPF: 7 Signs And Repair Options

Blocked DPF: 7 Signs And Repair Options

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A diesel-powered vehicle is equipped with a diesel particulate filter (DPF), though most are oblivious to its role or purpose.

Most of the time, you won’t know what it is until you see a warning sign on your vehicle’s dashboard.

What Is The Purpose Of The DPF?

The diesel particulate filter (DPF) in diesel-powered vehicles traps diesel particulate matter or soot in the exhaust system. It generally prevents exhaust from emitting black fumes into the environment. Once you notice black smoke moving out of the exhaust pipe, it’s clear that the DPF is no longer working optimally. The blockage will accumulate over time and necessitate routine cleaning like any other filter.

During normal operation, filters work in such a way that they can clean themselves regularly. Long periods of high-speed driving cause the engine to heat up, allowing the DPF to burn away any excess soot, a process known as passive regeneration.

Unfortunately, not everyone has the opportunity to engage in this type of driving, which leads to a clogged filter.

Manufacturers designed an active regeneration process for diesel vehicles if passive regeneration isn’t possible. It occurs once the DPF reaches a certain threshold of soot buildup. The engine control unit (ECU) will inject fuel into it to raise the engine’s temperature. It’s critical to finish the process because you’ll see a warning light if the filter remains partially blocked.

What Are The Indications Of A Blockage? 

Aside from the warning light on your vehicle’s dashboard and the emission of black smoke from the exhaust, there are other indications that you have a blockage. Depending on the indications, the filter may require regeneration, or you may use a diesel particulate filter cleaner, but professional servicing is recommended for the best results.

Here are some of the sure-fire indications of a blocked DPF.

  • Warning Light Illumination

The warning light on your vehicle’s dashboard is the initial sign of blockage. The filter is equipped with sensors that measure the pressure and temperature. If one of the sensors ends up stuck in its housing or breaks off, you can save on the costly replacement by replacing only the weld bungs instead of the entire filter. The weld bungs play a role in a diesel emissions system by stabilizing the sensors in the right place.

If there’s an inconsistency with the pressure, the warning light will illuminate your dashboard. It warns you that the filter requires regenerating to clear away the soot buildup. When both the DPF warning light and the engine management light are present, it indicates that the condition of your vehicle has declined to the point where it requires a diagnostic scan.

  • Reduced Fuel Economy

The DPF is designed to channel exhaust fumes from your vehicle’s engine. If there’s a blockage, the fumes have no exit point. As a result, it disrupts the engine since it can no longer function to its full capacity and minimizes fuel efficiency. You’ll spend more money on gas, and the accumulation of fumes in the engine can cause significant damage in the long run.

It’s best to monitor your average fuel consumption. When there’s a noticeable drop during your normal driving routine, it’s often indicative of a DPF blockage.

  • Engine Performance Deterioration

Poor fuel economy often goes along with a decline in engine performance. When a vehicle isn’t running optimally, the engine can no longer deliver the same performance, resulting in a noticeable drop in acceleration. You’ll notice this when you suddenly need more throttle input to maintain speed, especially on uphill terrain and on highways.

Furthermore, the exhaust has limited airflow, which results in lower performance because the engine cannot breathe properly and eliminate the exhaust gases.

  • Difficulty Starting The Vehicle

Although difficulty starting your vehicle can be caused by other engine issues, it’s a common problem if the DPF is clogged.

If there are any obstructions in the exhaust system, the engine will strain when starting. The problem is exacerbated when the engine is cold, especially in the winter.

  • Rough Idling 

Rough idling tends to occur along with poor fuel economy and engine performance. Rough idling typically occurs when the vehicle is warm but stationary or coasting in neutral gear.

You can easily distinguish this since the rev counter shifts upward and downwards without any input from the throttle. It can fall so low that the vehicle begins to vibrate as the engine tries to stall in some circumstances.

Rough idling is usually caused by a faulty engine, over-fueling, or the engine constantly adjusting to poor sensor readings or restricted airflow. All of these issues are caused by DPF blockage.

  • Increased Emission Of Black Exhaust Smoke

A diesel vehicle with a DPF shouldn’t generate large amounts of black smoke. If this happens, it means the filter is no longer functioning properly.

You must keep an eye out for the smoke discharge while accelerating. An option is to ask someone on the road if the exhaust pipe emits large amounts of black smoke emissions.

  • Limp Mode  

If you happen to overlook the warning light for a certain period, it only means that the filter will continue to end up with more blockage. It’ll reach a point when the limp mode activates to avert serious damage to your vehicle’s internal system. The mode also allows you to drive your vehicle safely over short distances.

When your vehicle switches to this mode, expect the performance to drop significantly. In most cases, you’ll be limited to several revs to protect the vehicle.

Final Thoughts 

A minor or major blockage in the DPF can be a hassle for many drivers. Knowing some of the indications of a potential blockage will allow you to deal with the issue before it can result in serious harm to your vehicle’s performance. The illumination of the warning light is the easiest way to tell that your filter has a blockage and can progress if you fail to take timely action. Some solutions worth considering include regeneration or having your vehicle serviced by a professional to get it running smoothly again.

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Anoj Kumar
Anoj Kumar
Anoj Kumar is the Editorial Director for the AutoFreak. Anoj has been consistently named one of the top Influencers and Author by independent organizations. He is a frequently quoted source in Auto-Mobile.
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