On average, it takes between thirty and sixty minutes to complete a forced regeneration. The substantial heat required for the regen renders the engine and aftertreatment system untouchable until it has time to cool down.
A forced regen occurs when soot builds up inside the diesel particulate filter (DPF) to the point that the vehicle is no longer operable. When this happens, a driver has to pull over and initiate a self-cleaning process that can take up to 40 minutes — valuable time that could have been spent on the road.
If your forced DPF regen lasts closer to an hour or continues beyond that, it likely suggests that your exhaust temperatures are not building up high enough to successfully burn off the soot collected in the DPF and that the truck is still trying to bring down those soot levels.
Force regeneration of the particulate filter
The ash from the engine oil accumulates on the inner walls of the ceramic and in the pores. This increases the pressures in the DPF and if clogged, can even damage the engine.
Regeneration, or regen, of the DPF filter, is the process that burns the soot accumulation that is inside the DPF filter. If you can no longer start a regen then you will eventually get stuck in a derate which will then lead to an engine shut down.
Monitor the Exhaust temperature and RPM. When the idle comes back down it means that the regen has finished. If the regen starts and stops then you may have a problem that prevents the regen from taking place.
An active regen cycle is a normal process that takes place as the truck is going down the road. A computer sensor monitors the DPF and a dashboard indicator light notifies the driver that the regen is taking place, or the DPF is now cleaning. “You'll notice a reduction in power during a regen,” notes Nace.
If both passive and active regens fail, and the DPF filter is in danger of clogging, the system will initiate a forced DPF regen. The driver will need to pull over while it happens.
Whenever it is necessary to perform a forced regen an engine oil change is required after the regen. Why, remember before how extra fuel is injected to get the DPF hot enough to regen, this extra fuel will dilute the engine oil.
How long does the regeneration take? The DPF regeneration cycle takes approximately an hour and a half (1 1/2 hours) to complete and can be completed as part of a routine service.
The DPF regeneration process creates very high exhaust gas temperatures and the exhaust will radiate a considerable amount of heat during and after DPF regeneration, and after you have switched the engine off. This is a potential fire hazard.
A DPF can last up to around 100,000 miles if maintained properly. After the car has exceeded that mileage, you could be looking at paying a large amount of money for a replacement - so always properly check MoT and service records when buying a used car.
The cost for a forced regeneration varies. Generally, it is between $300-$700 depending on the technician's required diagnostic time and the length of time your DPF regeneration lasts. How can I do a forced regeneration?
Active DPF regenerations need to burn extra fuel to achieve the high exhaust temperature for soot oxidation, which results in the increased fuel consumption rates.
DPFs need to regenerate (empty) themselves. Problems with regeneration may be caused by a town-based, stop-start driving style. Other possible causes include wrong oil type, incomplete combustion, and a low fuel level.
How Often Does DPF Regeneration Occur? Active regeneration happens roughly every 300 miles and is triggered by your car's electronic control unit (ECU) once your soot level is approaching 40 to 45%. Passive regeneration should occur when you take your car on longer journeys at higher speeds.
It can take anywhere from 5 minutes to over an hour depending on how blocked the filter is. During this time you should keep an eye on the engine temperature and make sure it does not overheat.
Depending on your driving, active regeneration may happen as often as once a day. If you do a lot of stop and go, it can happen even more often. Frequency depends on duty cycle and how much soot collects – as often as once a day or every other day An active regeneration could take up to one-half hour or more.
In a Diesel engine with a Diesel particulate filter (DPF) system, high-sulfur fuel causes white smoke containing odorous and harmful pollutants during DPF regeneration.
To make sure that the regeneration takes place, most manufacturers suggest that every few hundred miles, the car is driven for a period of more than 15 minutes at a consistent speed of more than 40mph. Doing this should kick-start regeneration and clear the filter.
Manual -- This type of regeneration occurs only when the vehicle is stationary, and it requires action on the part of the vehicle operator. The check engine light will illuminate on the vehicle dashboard, usually after an extended period of idling (when hydrocarbons build up and can cause overheating of the DPF).
It's telling you a parked regeneration is necessary, and you need to perform it as soon as possible. If your Check Engine light comes on while the DPF status light is flashing, it means you need to perform a parked regen right away. You may also hear a beeping sound to further alert you.