Hello. We guess you’re here because you want to know more about DPFs. We hope we’ve covered everything in this article for you, but if you need any more information, don’t hesitate to contact our team. We’re friendly, we don’t bite and we see plenty of DPFs each week.
1. What is a DPF (Diesel Particulate Filter)?
A Diesel Particulate Filter (DPF) is a device fitted to the exhaust system of diesel vehicles to reduce harmful emissions by capturing and storing soot particles Over time, the filter can become clogged and will need cleaning to maintain performance.
Since the legislation for Euro 5 Emissions came in 2009, DPFs have been fitted to diesels. It is a legal requirement for vehicles to have a DPF if they were originally fitted with one at the factory.
2. How do DPFs work?
DPFs trap diesel particles (soot) from the exhaust gases, which are then burned off during a regeneration process. This regeneration can happen passively (at high speeds) or actively (the engine injects extra fuel to increase the exhaust temperature).
Over time, if the regeneration doesn’t happen often enough, the filter can become blocked and require more intensive cleaning to function effectively again.
3. What can go wrong with DPFs?
Several issues can affect a DPF. If it becomes clogged due to failed or infrequent regeneration, it can cause a range of performance problems such as reduced power, higher fuel consumption and even damage to the engine.
DPF blockages are common in vehicles used for short, low-speed trips, which don’t allow for sufficient heat to regenerate. This is common in cars used primarily for short school runs or quick trips to the shops. We recommend a good blast down a motorway now and then to allow for regeneration.
4. Why do DPFs get blocked?
A DPF gets blocked when it accumulates more soot than it can burn off during the regeneration process. This is usually because the exhaust doesn’t get hot enough on short and slow journeys. Another cause can be faulty sensors or issues with the engine that affect how regeneration is triggered.
5. Why your DPF is blocked again
If your DPF keeps getting blocked, it’s likely that the conditions needed for regeneration aren’t being met or there is an underlying engine issue. A faulty fuel injector or turbo problem can also prevent regeneration from happening correctly, causing repeated blockages.
6. How do you know if there is a problem with your DPF?
Common signs of a blocked or malfunctioning DPF include:
- DPF warning light on the dash
- Drop in engine power
- Increased fuel consumption
- Black smoke from the exhaust
If you’re experiencing any of these issues, it’s important to book your vehicle in with a reputable garage to look into this. Ignoring these symptoms will cause further damage.
7. What happens when a DPF is blocked?
When a DPF is blocked, it restricts the flow of exhaust gases. This leads to higher back pressure in the engine. Which can in turn result in a loss of power, increased fuel consumption, and the potential for more severe engine damage if left unresolved. In severe cases, a blocked DPF can cause the vehicle to go into limp mode, limiting its speed and performance to prevent further damage.
8. What damage can a blocked DPF do?
A blocked DPF can cause extensive damage to your vehicle not addressed. The increased back pressure puts the engine, turbo and other components at risk. Overheating in the exhaust system can lead to serious mechanical failures. Early detection and thorough cleaning are essential to prevent costly repairs.
9. Can a blocked DPF fail an MOT?
Yes, a blocked DPF can cause your vehicle to fail its MOT test. During the MOT, inspectors check for excessive emissions, and a blocked DPF can lead to high levels of harmful pollutants. Also, if your vehicle was originally fitted with a DPF and it’s found to be missing or tampered with, it will automatically fail its test.
10. Can you drive with a blocked DPF?
Driving with a blocked DPF is not advisable. It can cause serious damage to your vehicle. Your engine, turbo and exhaust system are all at risk.
If your DPF is severely blocked, your vehicle may go into limp mode to try and protect itself from further damage.
11. Can a blocked DPF cause juddering?
Yes, a blocked DPF will most likely cause juddering, especially during acceleration. This happens because the blockage disrupts the flow of exhaust gases, leading to poor engine performance.
If you notice juddering and suspect a DPF issue, it’s important to have the filter checked and cleaned to restore smooth operation.
12. Can a blocked DPF cause rough idle?
A blocked DPF can contribute to rough idling because of the increase in back pressure.
13. Can a blocked DPF damage the engine?
Absolutely. If the DPF is blocked you are causing serious engine damage. All this built-up pressure forces the engine to work harder, which can lead to overheating and excessive wear. In extreme cases, it can result in complete engine failure. This is why it’s so important to address DPF issues early.
14. Can a blocked DPF cause turbo failure?
A blocked DPF can lead to turbocharger failure because of the increase in back pressure. This increase can lead to the turbo overheating and wearing prematurely.
15. What does a blocked DPF sound like?
You can expect to hear some unusual sounds coming from the exhaust, including whistling, hissing or excessive engine noise. These noises are the sound of gases struggling to pass through the clogged filter.
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Read More17. How do you clean a DPF?
Your car has the capability to clean the DPF through regeneration. However, if this hasn’t been done and the DPF becomes blocked, it’s time to step up your cleaning powers.
We are one of the very few garages in the area that provide Off-Vehicle cleaning. After removing the entire DPF unit, we place this in our DCS 20 Carbon Clean Machine. We test the filter first, then use high-pressure jetting with specialist cleaning detergents to remove soot and ash. The final step is the drying process, and then your DPF is ready to be refitted to your vehicle.
16. How to unblock a DPF?
If the regeneration process (burning off soot at high temperatures) isn’t cleaning your DPF, then it’s time to take it to the next level. There are many over-the-counter ‘DPF Cleaning Solutions’ you can buy, but trust us, these are nothing compared to actually taking the unit off the vehicle and properly cleaning it.
18. Do DPF cleaning solutions from shops work?
Over-the-counter DPF cleaning solutions may provide some short-term relief, but they are not as effective as professional cleaning. These solutions are generally used as additives that aim to assist regeneration but they can’t remove deep blockages. For long-term and powerful results, off-car cleaning is the way to go.
19. Does AdBlue affect the DPF?
AdBlue is used in Selective Catalytic Reduction (SCR) systems to reduce nitrogen oxide emissions and doesn’t directly interact with the DPF. However, the overall health of the exhaust system can affect both the SCR and DPF systems. Keeping both systems in check with regular maintenance will ensure optimal performance.
20. Can you remove a DPF from your vehicle?
To put it shortly, no. It is illegal in the UK. Vehicles fitted with a DPF from the factory must have it in place to comply with emissions standards. If removed, the vehicle will fail its MOT, and as the driver, you could face fines and invalidation of your insurance. The best option is to instead, keep your DPF happy with regular maintenance.
21. Should you buy a car with a DPF?
That depends on the driver’s preferences but yes, there is no reason to avoid a vehicle with a DPF.
These filters are necessary to ensure the vehicle is meeting emissions standards. However, it is still important to ensure that the DPF is well maintained. Regular vehicle servicing, especially for vehicles that perform a lot of low-speed or short-distance driving, will keep the filter in good condition and avoid costly repairs.