Complete Guide To Diesel Particulate Filters
What This Guide Will Cover
With all modern diesel vehicles now being fitted with DPF’s (Diesel Particulate Filters), many drivers are concerned about, or are having issues with them blocking up & causing problems during ownership.
We’ve produced this complete & comprehensive guide which covers & discusses the following:
- What Is A DPF Filter
- Why Are DPF Filters Fitted
- How Do Diesel Particulate Filters Work
- What Problems Can DPFs Cause
- What Causes Blocked DPF Filters & How to stop your DPF from becoming blocked
- What To Do If Your DPF Is Blocked?
- What Is DPF Regeneration
- Can Remapping Help Reduce DPF Issues
- Can You Remove DPF Filters
- What Is DPF Removal & DPF Delete
- Is DPF Removal Legal
- Why You Shouldn’t Remove Your Car’s DPF
- DPF Testing Bill Passed – Feb 2022
- Our Stance On DPF Removal
- The Governments Stance On Removing Diesel Particulate Filters (From their Web Page)
Whilst the manufacturers have included an automated DPF cleaning process into the running of the vehicles, a TerraClean service will further enhance the cleaning of your DPF & help prevent problems.
Just click the button below to get a price to TerraClean YOUR specific vehicle.
What Is A DPF Filter
A Diesel Particulate Filter (or DPF for short) looks very similar to an exhaust silencer, in that it is a metal canister fitted in the exhaust system of a modern diesel vehicle.
It is an integral part of the exhaust system & placed close to the engine to filter & capture the exhaust soot generated when the engine is running.
Why Are DPF Filters Fitted
DPFs are designed to trap the microscopic emissions produced by diesel engines which would have previously been emitted as poisonous gasses into the environment.
If this ‘soot’ is not filtered out, these diesel particulates pollute our air and can damage our health, so these filters are vital in keeping our air clean and protecting us from pollution.
Since 2013 when the Euro 5 standard came into force, all new diesel vehicles have been fitted with a DPF (Diesel Particulate Filter) in the exhaust to meet the updated emissions standard & filter out poisonous gasses which pollute the air. In fact, many pre 2013 vehicles will have one fitted in anticipation of the updated standards.
The emission standards were updated to aim to achieve an 80% reduction in diesel particulate (soot) emissions
Diesel particulate filters are important in maintaining acceptable levels of air quality..
Regain Performance
The removal of carbon deposits improves overall vehicle performance with a increase in drivability
Restore MPG
When motoring journalist and TV presenter Quentin Willson reported a 14% improvement in MPG . people were eager to try TerraClean.
Reduce Emissions
The innovative service will remove most deposits from your engine and make sure that every cruising mile is as clean or greener then before
Preventative Maintenance
Every TerraClean service you perform on your car will remove carbon and gummid, which helps prevent problems from occurring in the future!
Why Are DPF Filters Fitted
DPFs are designed to trap the microscopic emissions produced by diesel engines which would have previously been emitted as poisonous gasses into the environment.
If this ‘soot’ is not filtered out, these diesel particulates pollute our air and can damage our health, so these filters are vital in keeping our air clean and protecting us from pollution.
Since 2013 when the Euro 5 standard came into force, all new diesel vehicles have been fitted with a DPF (Diesel Particulate Filter) in the exhaust to meet the updated emissions standard & filter out poisonous gasses which pollute the air. In fact, many pre 2013 vehicles will have one fitted in anticipation of the updated standards.
The emission standards were updated to aim to achieve an 80% reduction in diesel particulate (soot) emissions
Diesel particulate filters are important in maintaining acceptable levels of air quality..
How Do Diesel Particulate Filters Work
Inside each DPF is a complex honeycomb ceramic structure designed to filter the exhaust gases, whilst also minimising the reduction in flow of the exhaust gases, so as not to reduce the performance of the vehicle.
As the exhaust gases flow through the filter walls inside the DPF, the particulate matter (soot) is deposited on the walls, therefore reducing the amount of black smoke & harmful air pollution.
When these filter walls inside the DPF reach a certain saturation level, the vehicle needs to perform a regeneration cycle, which aims to burn off the particulate build-up inside the filter, rejuvenating them to continue filtering.
This regeneration can only occur at high temperatures, typically reached when a vehicle is driven at moderately high speed. Diesel drivers who mainly drive in built up areas, and only usually travel at low speeds & for short distances can suffer with blocked DPFs, as their vehicles don’t regularly reach the conditions necessary for regeneration to occur.
And if the DPF is not regenerated regularly, through longer motorway journeys for example, the filter may need to be manually cleaned, or even replaced, which can be costly for the vehicle owner.
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What Problems Can DPF's Cause
Because the DPF filters out the ‘soot’ from the exhaust gases, these particulates build up inside the filter, reducing the flow of exhaust gases.
If the build-up of particulate matter is not removed from the filter, the flow of gases can be severely restricted, causing a loss of power & increased use of fuel (to try to off-set the power loss). The vehicle may also be harder to start up & get running.
Also because of the restriction, the smell of exhaust gasses may become more noticeable both outside & sometimes inside the vehicle.
In very severe cases, the increase in back-pressure caused by a significantly blocked Diesel Particulate Filter can cause damage to some of the engine components, such as the turbo
What Causes Blocked DPF's & How To Stop Your DPF From Becoming Blocked
The whole diesel emissions system (including the DPF) has been designed to be maintenance free, but does rely on certain circumstances & parameters to be met.
Whilst the emissions system needs no maintenance, it does require your vehicle’s engine to be correctly & well maintained, to ensure it is not causing problems which will affect the functionality of the DPF.
For instance, ensuring the correct oil is used, that the air filter is not blocked/restricted & that the EGR valve is working properly are 3 significant factors which could affect the performance of the Diesel Particulate Filter.
In many vehicles, a low ash oil should be used to reduce the amount of solids/soot which will be trapped in the DPF, and an incorrectly function EGR valve (Exhaust Gas Recirculating valve) could also add more ‘dirty’ exhaust gases to be cycled through the exhaust system.
Also, incorrectly functioning fuel injectors can cause Diesel Particulate Filter problems with incorrect fuel/air mixtures not burning properly & causing more soot to be generated.
All this said, probably the main cause of a blocked DPF is not driving the vehicle in a way which allows the DPF self-cleaning (regeneration) process to activate & complete it’s cycle, to burn the soot of the filter & turn into ash in the bottom of the canister.
See our section on DPF regeneration for more details.
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What To Do If Your DPF Is Blocked?
If your warning light has come on for the first time, taking your vehicle for a decent ‘spirited’ run’ – basically you need to be going faster than 40-50mph – should activate the DPF regeneration process which should be enough to clear the build-up of ‘soot’ inside the filter.
However, if this doesn’t resolve the problem & the light stays on, and your car’s performance is impaired, or you notice strong exhaust smells, then you might have to look at other solutions.
A lot of DPF issues are caused from underlying issues which need to be diagnosed by a DPF specialist (or a reputable garage) who knows what they are doing and not just relying on a diagnostic read out. This is a big problem as for example a blocked air filter can cause the DPF to block, so the source of the problem needs to rectified.
There are a few options you can consider:
- An experienced garage should be able to run a diagnostic check & identify if a ‘forced regeneration’ is possible & should clear the DPF
- After diagnosing the problem & state of blockage, a DPF cleaning specialist (such as TerraClean) may be able to carry out a DPF clean with the DPF still fitted. If it is severely blocked, it may need to be removed, cleaned & refitted.
- If the DPF is too blocked, it may need to be replaced, and in some very severe cases, other items (such as turbos) may also need replacement
What Is DPF Regeneration
The whole diesel emissions system (including the DPF) has been designed to be maintenance free, but does rely on certain circumstances & parameters to be met.
Whilst the emissions system needs no maintenance, it does require your vehicle’s engine to be correctly & well maintained, to ensure it is not causing problems which will affect the functionality of the DPF.
For instance, ensuring the correct oil is used, that the air filter is not blocked/restricted & that the EGR valve is working properly are 3 significant factors which could affect the performance of the Diesel Particulate Filter.
In many vehicles, a low ash oil should be used to reduce the amount of solids/soot which will be trapped in the DPF, and an incorrectly function EGR valve (Exhaust Gas Recirculating valve) could also add more ‘dirty’ exhaust gases to be cycled through the exhaust system.
Also, incorrectly functioning fuel injectors can cause Diesel Particulate Filter problems with incorrect fuel/air mixtures not burning properly & causing more soot to be generated.
All this said, probably the main cause of a blocked DPF is not driving the vehicle in a way which allows the DPF self-cleaning (regeneration) process to activate & complete it’s cycle, to burn the soot of the filter & turn into ash in the bottom of the canister.
See our section on DPF regeneration for more details.
Can Remapping Help Reduce DPF Issues
Whilst a remap will make the engine work more efficiently & help reduce the emissions with a better fuel/air set-up for this country, it will not overcome the need for the DPF to regenerate, and for the engine to be serviced & maintained correctly.
It will also not overcome the problems caused by short, stop-start journeys never letting the engine get to a state where it can initiate a regeneration.
So in short, it may help marginally, but not significantly.
Can You Remove DPF Filters
It is technically & practically possible to remove a DPF from the exhaust system, and for the vehicle still to opertate satisfactorily.
This is how vehicles used to be before the laws were changed to reduce pollution in the environment.
If the vehicle was being used off-road, then an owner may choose to do this. But the DPF removal should also be done in conjunction with a DPF software delete too.
What Is DPF Removal & DPF Delete
In our terminology, DPF removal & DPF deletes are 2 separate things. One refers to the physical hardware of the DUesel Particulate Filter, and the other refers to the associated software in the ECU (Engine Control Unit – or engine management system).
Some owners will remove a DPF in 1 of 2 ways.
The first is to physically cut out the DPF canister from the exhaust and replace it with a straight-through pipe, making it as though the DPF filter had never been installed.
The second & most common way is to remove the diesel particulate filter, cut it open, smash out the filter elements inside, weld it back up & refit it to the vehicle. This makes it appear to be fitted, but obviously not functioning.
Some remapping companies will offer to map out the DPF, which means they will remove the software which triggers the DPF regeneration process, and the dashboard DPF warning codes.
This would be a very bad thing to do if the DPF was not removed, as the filter inside would continue to block up & eventually cause major engine damage.
Is DPF Removal Legal
Many owners want to know can you remove a DPF legally.
Removing the Diesel Particulate Filter may be considered by some vehicle owners as a cheaper way of sorting out a DPF problem in their vehicle, when compared to buying & fitting a new one. Whilst this may be true in the short-term, the long-term costs of removing a DPF could be huge.
Since February 2014, as part of the MOT test, the tester should inspect the exhaust system of a diesel vehicle to check there’s a functioning diesel particulate filter. A missing DPF, where one was fitted when the vehicle was built, will result in an MoT failure.
In February 2022, a new bill has been passed where the MOT test will have stricter rules on testing the presence & functioning of the diesel particulate filter, if the vehicle should be fitted with one.
So whilst it’s not illegal to remove the DPF from your vehicle, it is illegal to drive your vehicle on the public highway without a DPF if one should be fitted, as it is an offence under the Road vehicles (Construction and Use) Regulations (Regulation 61a(3))1 to use a vehicle which has been modified in such a way that it no longer complies with the air pollutant emissions standards it was designed to meet.
The potential penalties for failing to comply with Regulation 61a are fines of up to £1,000 for a car or £2,500 for a light goods vehicle.
Some other remapping companies will remove & remap the DPF out, but beware, as it will make your vehicle unroadworthy. But the remapping company will hide behind the fact that it’s not wrong to offer the service, it’s only wrong for the owner to use that vehicle on the road after they’ve done it.
But you’ll be the one with a vehicle that will not pass a valid MOT test & will be faced with the cost of rectifying the issue.
Regain Performance
The removal of carbon deposits improves overall vehicle performance with a increase in drivability
Restore MPG
When motoring journalist and TV presenter Quentin Willson reported a 14% improvement in MPG . people were eager to try TerraClean.
Reduce Emissions
The innovative service will remove most deposits from your engine and make sure that every cruising mile is as clean or greener then before
Preventative Maintenance
Every TerraClean service you perform on your car will remove carbon and gummid, which helps prevent problems from occurring in the future!
Why You Shouldn’t Remove Your Car’s DPF
There are 2 main reasons why you should not remove a DPF filter from your vehicle
- DPF Removal fines – If it is proven that the Diesel Particulate Filter (DPF) has been removed from your vehicle, you can be fined up to £1,000 for cars and £2,500 for vans.
- Pollution From DPF Removal – These filters were designed to meet air pollution standards, which aims to improve the quality of the air we all have to breathe, and to protect the environment. Whilst we understand that there are costs involved in repairing or replacing DPFs, they’re fitted to help protect our health & the future of the world we & future generations live in.
DPF Testing Bill Passed – Feb 2022
A new bill has been passed in Parliament in Feb 2022 to introduce the stricter testing of DPF’s (Diesel Particulate Filters) during MOT tests.
Although it is currently part of the MOT test that if your DPF is not functioning correctly, not at all, or been removed & mapped out, your vehicle will fail it’s MOT & be unroadworthy until rectified.
This bill will enforce stricter & more in depth testing of the vehicles emissions & DPF’s, which will identify vehicles which have DPFs removed, gutted and/or remapped out.
The Governments Stance On Removing Diesel Particulate Filters (From their Web Page)
There are 2 main reasons that some people might want to remove a vehicle’s diesel particulate filter.
- Performance – Some garages claim removing a vehicle’s diesel particulate filter will improve its performance and make it more economical to run.
- Cost – Some garages also claim that removing the particulate filter is cheaper than replacing an old blocked up filter with a new one.
However, it’s illegal to drive a vehicle that’s been modified in that way.
MOT ‘friendly’ removals
Our enforcement team recently investigated 2 linked companies, who were offering to remove diesel particulate filters from vehicles – describing their services as being “MOT friendly” and “hard to notice”.
Both companies regularly recommended each other on social media, but claimed to our investigators they had no official relationship, despite sharing the same address, staff and directors!
As a result of our investigation, we found the directors of the diesel particulate filter removal company were authorised testers. These MOT testers were banned from conducting MOT tests for 2 years and the owner of the MOT station was banned for 28 days.
Serious consequences for testers and garages
The bans give a clear message about the importance of maintaining the integrity of the MOT. Remember, the consequences of turning a blind eye to a missing diesel particulate filter (or worse, actively taking part in their removal) can be serious for an MOT tester.
A vehicle that needs a particulate filter and doesn’t have one should fail its MOT. If you pass it knowing that it doesn’t have one, you’re harming the environment and committing fraud.
Fines for drivers
For drivers, the penalty for driving a vehicle with the diesel particulate filter removed, are fines of up to £1,000 for a car or £2,500 for a light goods vehicle.
Undeclared illegal modifications (like removing a diesel particulate filter) could also invalidate a vehicle’s insurance, so it’s not just garages who could face serious consequences.
Maintaining integrity
During 2016 to 2017, we issued 761 warnings or disqualifications to MOT garages or testers who carried out improper tests, putting all road users at risk. That’s a tiny proportion of the 60,000 or more MOT testers in Britain.
We know the vast majority of you wouldn’t ever consider making modifications to cars that make them unsafe – and illegal – to drive. It goes against everything the MOT stands for, and as MOT testers, you’re at the forefront of making sure the MOT’s integrity is maintained.
Visit the Governments information page here.
Our Stance On DPF Removal
We get asked on a daily basis to remove/remap out DPFs & EGR valves which are part of the emissions system, and need to be functioning to pass an MOT, and although we have the capability to do this, we turn them away day in & day out, advising the owners it’s not the right thing to do which is why we won’t do it.
It is frustrating that there are other unscrupulous remapping companies who will remove/remap the DPF/EGR out, which then makes the vehicle unroadworthy, but hide behind the fact that it’s not wrong to offer the service, it’s only wrong for the owner to use that vehicle on the road after they’ve done it!!
They KNOW the vehicle will be used on the road, but they are happy to put profit before doing the right thing!
Unfortunately for the vehicle owner who’s had this removal service, the more stringent checks will now identify the DPF issue & mean their vehicle will fail an MOT test.
At this stage we are unsure if the vehicle owner will have a legal claim against the company who carried out the DPF removal service.
You would hope that any self respecting business would at least refund/compensate the vehicle owner for the cost of the service, having carried it out knowing that it makes the vehicle unroadworthy.
We’ll make further posts about this new bill as and when more details become available.
Why Choose TerraClean Shrewsbury?
01
Quick Process
The whole process is a ‘drive in – drive out’ service and usually takes around 1 hour for most vehicles. You usually need to pre-book to arrange to have the work carried out, but we may be able to squeeze you in on the same day.
Just call us on 01743 466100.
02
Value
With the cost of the service for most vehicles being just over the hundred quid mark, we think it’s great value to keep your injection system, cylinder head, valves, piston crowns, catalytic converter, DPF filter and exhaust in great condition.
03
Proven
This isn’t a ‘here today – gone tomorrow’ service. It is a long standing and proven system which has been developing in North America over the past 6 years or more. There is plentiful data to prove the improvements we claim with regard to increases in BHP, better fuel economy and lower emissions.
04
Value
We offer this service as part of our range of high quality products and services at Ace Car Care. We always aim to give great service at a great price, and will not compromise our standards just to save a few quid. So you can be sure you’ll get our best attention at all times.