To regenerate a Diesel Particulate Filter (DPF), you generally need to drive for 20-30 minutes at a consistent speed of 60 km/h (around 37 mph) or higher, ideally on a highway or dual carriageway, to reach the necessary exhaust temperature (around 600°C) for passive or active regeneration to occur. The distance varies, but it's the sustained time and speed, rather than a fixed distance, that triggers the burn-off, with highway drivers needing fewer regenerations (every few hundred km) than city drivers.
Typically, a regeneration cycle can take anywhere from 20 to 30 minutes to complete under normal operating conditions. However, in some cases, it may take longer if the DPF is heavily loaded with soot or if the vehicle hasn't reached the required operating temperature for regeneration to occur efficiently.
Passive DPF regeneration
Passive regeneration occurs when the car is running at speed on long motorway journeys which allows the exhaust temperature to increase to a higher level and cleanly burn off the excess soot in the filter.
So don't ignore it, hoping the DPF light will simply go away. You need to go for a drive where you can get the car up to temperature and keep the revs up - preferably above 3000rpm - for a good few minutes.
The driver may notice an indication on the dashboard when passive regeneration is taking place. In such a case, the driver must continue driving and avoid parking the vehicle as it may not support the regeneration process.
Will I Know When DPF Regeneration Is Happening?
REDUCE IDLING
Even at low engine speeds particulates are emitted by your engine, so keeping your engine ticking over when you're parked or not moving can clog your filter quicker, because DPF regeneration cannot occur at idle.
How does DPF regeneration occur? The regeneration occurs automatically, usually without the driver being aware that it is taking place. In the majority of cases, the process is carried out when the engine and exhaust system has reached normal operating temperature and the vehicle is travelling at over 40mph.
If your car has an automatic gearbox, change gears in manual mode, increasing the number of revolutions. However, there's no need to go as far as the rev limiter, as that won't do any good. Drive in this mode for at least 30 minutes. This will trigger a regeneration cycle and your DPF will be cleaned.
Use the Correct Engine Oil
Using the wrong type of engine oil can also cause DPF problems. The engine oil should meet the vehicle manufacturer's specifications, and it's essential to use low-ash oil designed for diesel engines equipped with DPFs. High-ash engine oil can produce more soot, which can clog the DPF.
Top 10 vehicles with DPF issues:
Passive Regeneration
If you have mostly driven your diesel car around town and notice that the DPF is becoming blocked, take the car out on a long, motorway journey in an attempt to burn off the soot. On the motorway or dual carriageway, use a gear down (5-speed use 4th and 6-speed use 5th) to increase the engine revs.
In fact, driving is usually the best way to allow regeneration to complete. The system relies on heat and airflow. A steady cruise at 60 km/h or more gives the DPF the conditions it needs to burn off soot. City stop-start driving can interrupt the process.
Keep It Steady: Keep the car in 4th or 5th gear and aim for around 2500 rpm. Avoid harsh acceleration and heavy braking. It's all about consistency! Drive On: The regeneration process typically takes about 30 minutes of continuous driving.
However, the burn-off temperature of approx. 600 °C is not reached on short distances. This results in the diesel particulate filter becoming clogged over time and increased fuel consumption as well as engine problems may occur.
To remove the excess buildup, a process known as DPF regeneration is used, which can be performed either while driving or stationary.
Active regens are initiated by the truck's computer and typically occur while the truck is driving. Passive regens are done while the truck is idling. This type of regen is less efficient than active regens.
You should consult the handbook for your vehicle for more specific guidance on how you should drive to initiate regeneration of the DPF and clear the warning light. Nevertheless, a general rule of thumb to follow is that you should run the engine at least 40 mph and at least 2500 rpm.
8 symptoms of blocked DPF
The concern is that stopping regeneration too early leaves soot particles behind, and they just keep accumulating and getting harder to remove. Eventually, the filter can become so blocked it affects the engine's ability to run properly. And that could cause problems.
Faulty or dirty injectors can produce an improper fuel spray pattern, leading to incomplete combustion and excess soot. This raises the soot load in the DPF and can cause repeated or prolonged regens.
The worst things for a diesel engine involve neglecting maintenance (especially oil/filters), using poor fuel quality, allowing low fuel levels, overloading/lugging the engine, and not letting it warm up/cool down properly, all leading to contamination, excessive wear, turbo damage, and injector/pump failure due to high pressures and sensitive components. Contaminated fuel (water, dirt, high sulfur) is especially damaging, corroding parts and clogging filters in these high-pressure systems.
Active or passive regeneration
Active regeneration takes place about every 300 miles, whereas passive regeneration takes place whenever you drive at sufficient speeds for about 30 minutes while exceeding 2,500rpm.
This can reduce engine performance and efficiency over time. Fuel Contamination: When a diesel engine idles for long periods of time, it doesn't reach its optimal operating temperature. This can cause unburned fuel to dilute the engine oil, leading to increased wear and tear on engine components.