I’ve you’re an owner of a modern vehicle with a diesel-powered engine, then you must have heard the term ‘DPF reset‘. What you may not have heard (or don’t understand) is the passive vs active vs forced DPF regeneration jargon.
While extremely simple and easy to understand, these terms all refer to a type of Diesel Particulate Filter Regeneration and curiously, aren’t the same thing. The terms, though all referring to various regen types, aren’t also synonyms (or interchangeable).
Today, I’ll be taking you by the hand and explaining (like you’re five), all you need to know regarding passive, active, and forced DPF regenerations. However, before I proceed, first things first: what’s a DPF regen, and why do you need to have one done in the first place?
Article Outline
What’s a DPF Regen & Why Do You Need to Have One Done?
If you use a diesel-powered vehicle, there’s a great chance that you’ve already seen the ‘Regen Needed’ service reminder light illuminate on the cluster (your manufacturer may employ slightly different language, meaning the same thing). Your mechanic may have quoted a figure north of $500 to get the light sorted and the vehicle returned to full operational ability. Confused, you rightly refrain from paying the quoted sum, instead opting to run a little research and be more informed before parting with your money.
Smart decision.
Suppose you’re a heavy-duty diesel user of agricultural or construction machines, your machinery may have likely gone into limp mode, decided to operate at a fraction of its capacity/ability, or at the moment, is/are generally useless. Called, the dealer insists that to get back in business, you need a DPF regen, and he also runs you a quote. A quote you don’t like.
Confused, you’re determined to figure out what a DPF reset is and possibly, if you can do without it.
In a past article, DPF Regeneration: What It Is, Why It Matters & How to Perform It, I explained in detail what a DPF reset is and why you need to periodically consider it.
However, if you’re not open to looking at that article now, a Diesel Particulate Filter Reset is the process of burning the soot collected in the diesel particulate filter into harmless ash.
The end game is to have cleaner exhaust gases and overall, have cleaner air to breathe in the cities, the country, and the freeway, where most of the diesel machines are found doing their thing.
This leads, logically, to the three (3) major types of DPF resets currently obtainable.
Passive DPF Reset
A passive DPF reset works in the background, silently, trapping soot released as by byproduct of the diesel combustion process.
How this happens is simple: around the 3k RPM mark, the exhaust system heats up to around 500°C (932°F) and beyond. At this point, the soot trapped in the Diesel Particulate Filter easily burns away as you drive normally, provided you keep sustained RPMs for between 10 and 30 minutes, depending on make, model, and year.
If a passive DPF reset works as it should, there’s usually no need for any other type of regeneration as long as the vehicle continues to work in a manner that keeps the system running around that threshold, periodically.
Active DPF Reset
However, it’s not always a passive DPF reset happens. This is especially true for vehicles driven exclusively in heavy city traffic, where the exhaust doesn’t get to heat up to (or around) 500°C (932°F).
When that’s the case (and soot accumulation in the DPF reaches up to around 80% of its holding capacity), a service reminder light shows up on the cluster, encouraging you to perform a reset at your earliest convenience.
Doing this is simple and involves parking the vehicle on plain, dry ground, making sure that the engine is warmed up to operating temperature, and starting the DPF reset procedure by flipping the DPF function switch.
Depending on make, model, year, and state of particulate accumulation, this process can last anywhere from 20 minutes to an hour. While it lasts, the idle engine speed rises and falls, and black smoke may be emitted from the tailpipe.
Forced DPF Reset
Sometimes, however, both a passive and an active DPF reset fail (or don’t work as intended). When this is the case, the last resort (shy of replacing the particulate filter itself) is a forced DPF reset.
A forced DPF reset serves the same purpose (of burning trapped soot in the particulate filter) as the passive and active DPF resets. The difference, however, is that a forced DPF reset makes use of a dedicated scanner, often capable of commanding OE functions such as the Ancel HD 3600.
A forced DPF reset is the only DPF reset type that needs external intervention, and in most cases, is also financially taxing. Usually, this DPF reset type takes about an hour from initiation to completion.
Passive vs Active vs Forced DPF Reset: Which Is Best?
A passive DPF reset happens on its own; an active reset asks you nicely for a regeneration act, and a forced regen only ever happens when all the other options fail, and the vehicle needs to perform the regen compulsorily either because it’s in limp mode, working at half capacity or generally, screwing up driveability or operability.
So, which is better or preferred?
None, as a matter of fact. Every other thing being equal, a passive regen happens all the time, and the other two aren’t needed.
However, when the passive option fails, the other two – active and forced – are two failsafes that, like the classic knight in shining armor, save the day.
Love the Above? Subscribe for More
Throttle Lan
DIY Mechanic and Freelance Auto Writer