Bryan’s Garage team is certain that most seasoned drivers are no strangers to the concept of diesel particulate filters.
Yet, many newcomers still overskip it during their first drive, which can leave severe consequences for their vehicles in the long run!
That’s the reason we craft this insightful guideline, aiming to shed light on every relevant facet of this device.
So what does it do, and what does it mean when the diesel particulate filter warning light is turned on?
You will receive the answers in a blink. Keep scrolling for more!
How Do Diesel Particulate Filters (DPF) Work?
1. DPF Filtration
A DPF shares the same mechanism with an oil filter, with the fluid being the only difference.
It operates by capturing particles and dirt matter from your car’s engine exhaust to keep them from slipping onto the streets.
Unlike catalytic converters – designed for reductions of gas emissions via the catalyst – this filter aims to retain and trap these particles until they get burned or oxidized in DPFs thanks to a process named “regeneration”.
Given the good durability of ceramic, this material is often used to make DPFs. Some widely-favored ceramic materials include aluminum titanate, silicon carbide, and cordierite.
The most popular DPFs in common usage are honeycomb ceramic cellar filters, which arrive with plugged channels at different ends.
Arranged in checkerboard patterns, these ends push your shoot-containing exhausts to pass through filtered porous walls.
More specifically, the particles stay trapped in filter pores and on the top of walled channels during the entire process.
Due to the honeycomb structures, they offer huge filtration areas while cutting pressure losses. This success makes them the commercial standard of wall-flow filters for most DPF applications these days!
So how does this entire process occur, exactly? First of all, soot particles are trapped in your inlet channels, whose front end is wide open, and the back ends are plugged.
Each filter has hundreds of cells/channels for every square inch (or cpsi), with 200 cpsi being the most used.
As 50% of these channels have been front-plugged (while the rest are back-plugged), that means only 50% of them can gather ash or soot.
In simpler terms, only channels accessible from the inlet sides are vulnerable to dirty exhaust flows, while those from the outlet sides stay clean.
Considering the honeycomb design and small-sized pores, DPFs easily achieve more than 99% trapping efficiency, guaranteeing no ash or visible soot can pass through their filter walls.
But what if you still see streaks of soot in your outlet channels? That only indicates one thing: your car is experiencing filter failures.
2. Filtration Regenerations
To cut down filter pressure drops from soot accumulation, DPFs will regenerate via a process that burns (or oxidizes) existing soots.
Regeneration procedures fall into two wide categories, though most applications like to combine them both.
That’s mostly true with equipment or vehicles experiencing low temperature exhaust operation (such as low speed/load/idle operating cycles).
Active Regeneration
Active Regenerations call for extra heat added to the exhausts, which increases the soot temperature to the required oxidation level – with the help of the exhaust’s excess oxygen.
The oxygen soot combustion should be at least more than 1000°F (or 550°C)
As those high temps do not occur in regular engine operations, experienced mechanics actively employ numerous strategies to increase those temperatures.
One case in point is the inclusion of diesel burners to heat all the exhaust invading DPFs. Another example is the DOC (diesel oxidation catalysts) that burns diesel fuel and raises the filtered heat.
DOC usage also needs extra diesel exhaust fuel, accomplished via a hydrocarbon doser/fuel injector installed in the DOC’s exhaust upstream or in-cylinder methods.
Other active regeneration forms are microwaves, plasma burners, and electric heating.
Passive Regeneration
As implied by the name, this process does not need extra energy for the regeneration procedure.
Rather, it depends on soot oxidation in NO2 presence, which can happen at lower temps from 481°F to 751°F (251°C to 401°C).
Catalysts are used to change NO in the exhausts into NO2, necessitating precious metals for reaction facilitating (such as Pt – platinum). Hence, do not be surprised that the system’s cost can be expensive.
Under rare circumstances, catalyst coatings are directly applied to DPFs, catalyzed DPFs (C-DPFs), or DOCs.
Even more surprising, some commercial systems combine both the C-DPF and DOC for better efficiency.
In short, the entire process produces NO2 and oxidizes soots at temps that take place during standard vehicle or engine operation.
If things go well and passive regeneration takes little time, then you don’t even need active regeneration.
However, from what we know so far, low temp operation often wastes lots of time (ex: low load/idle operation), especially in cold weather, which is why active regeneration might still play a crucial role.
Still, are there any alternatives to produce passive regeneration without active ones? Fortunately, yes! In those cases, a high-temp operation can supplement low-temp ones to generate passive renewal.
Diesel Particulate Filter Warning Light Issues
1. What Does It Mean When The DPF Light Is Turned On? DPF Light Meaning
Once the soot levels in the filter reach a certain benchmark (often around 45%), your engine will strive to reduce them – and turn on DPF regeneration light to inform you in case of failures!
To explain, as you keep driving, the automobile computer will monitor soot levels within the filter, determining whether regeneration is a must.
That way, the system can let you know that soot is accumulating inside the pipes.
And what will happen if you decide to ignore it? Soot will build up until your car computer switches to “limp” mode to keep damage at bay.
This mode restricts your speed and hampers driving performance in general!
2. What Makes Them Turned On In The First Place?
As previously discussed, blocked particulate filters are the most common cause of DPF warning light displays.
These lights indicate that your onboard computer program has sensed excess soot in the pipes, triggering the car into limp mode.
Another reason behind this dilemma might be a defective temperature or pressure sensor.
When these parts malfunction, they send incorrect signals to your onboard computer systems, unnecessarily activating the DPF light on dash!
However, keep in mind that the second case is rare. Excess build-up of soot still remains the major cause.
3. Diesel Particulate Filter Warning Light – How to Fix
Drive Above 40 MPH
Upon the first time seeing the light, you can drive as usual without problems.
Still, whenever you have the chance, bring the vehicle onto highways and drive at 40 MPH for approximately ten minutes. Click here if your car can’t go over 40 MPH.
At the same time, keep an eye on the engines to keep them around 2600 RPM. That can raise the temp enough for filter generation – and, hopefully, will turn off the diesel particulate filter light!
If you choose this solution, remember to stay far from the active regions in the city. Choose a place that’s as traffic-scarce as possible!
By now, lingering clogs will transform into gas, exiting via the exhaust. Should the light still refuse to turn off, stretch the period for another fifteen to thirty minutes!
Apply Cleaning Additives for Your DPF
Another approach that can clear block DPF filters is to purchase DPF additives! It’s easy to get options as cheap as below $15 – and apply them to the car’s fuel tank.
Make sure you always stick to manuals and manufacturers’ recommendations during the entire process! Once done, kick start the engine and drive the vehicle around for fifteen to forty minutes.
Within that period, your warning light should automatically shut off – resulting from consistent addictive circulation inside the systems.
So yes – rather than asking us, “How long can you drive with DPF light on?“, you should tackle the problems right away.
4. How Often Should You Replace Your DPFs?
It’s hard to deduce a good estimate since many different car models are available.
Nevertheless, regular cars or trucks with heavy-duty cycles and frequent stops should clean their DPFs every 100,000 miles.
For those of less severe cycles, it’s alright to wait until 200,000 miles or 250,000 miles.
Meanwhile, trucks with 11- to 14-liter engines (class 8) should survive 250,000 miles, easily going to 400,000 or even 500,000 miles without DPF replacement.
Of course, the mileage and hours still rely on your duty cycles.
So, in general, how you use your car will decide whether cleaning is necessary and when! Low-ash, clean, and good diesel is the key to better longevity.
5. How Much Will It Cost To Replace DPFs?
How much will DPF cost? The calculation differs since we have thousands of options for re-installation, cleaning, and replacement alternatives (full or partly?).
But overall, it’s safe to say that standard costs for brand-new filters often start around $1000 and gradually build up from there.
Besides the filter, we must also count labor prices in the total sum. Hourly pay rates for service centers or mechanics should also be well-considered: $18 to $25 is the most common range.
But that might also change depending on the services’ expertise, skills, and levels.
Not many shops offer DPF replacements as flat tasks. They also demand charges based on:
- Model and make
- Whether you use aftermarket DPFs or OEMs
- Service range aside from the re-installation
- Whether you should have your filters cleaned
- Issues with ignition, fuel mixture, engine timing, et cetera.
- Complete history check for the vehicle.
- Technical problems with pressure and temperature sensors (which might need replacements as well).
Conclusion
This article has discussed why diesel particulate filter warning light flashes on your car’s dashboard and also provided appropriate solutions.
Remember to change them often and monitor how they work during your driving trips!
For more guidance on other automobile filters, keep browsing our website!