Manual regeneration is often required when vehicles are driven at insufficient speed to allow regeneration to be carried out automatically by their engine management control software. The vehicle is already suffering with driveability and lack of power problems.
If the driver doesn't take the appropriate action, however, the soot accumulation reaches 75 % and another warning light should appear. In this stage, the car needs a 'forced' regeneration, which can only be undertaken by a dealer or workshop. Without forced regeneration, soot accumulation will reach levels above 85%.
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.
Here's how to look after your particulate filter
All you have to do is get your car on an A road or motorway on a regular basis, such as every 300 miles. You then need to run it for 10-20 minutes at speeds in excess of 40mph. This will heat up your exhaust and burn off any soot in the filter.
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.
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.
*set a timer* Wait for the regeneration to start. Monitor the Exhaust temperature and RPM. When the idle comes back down it means that the regen has finished.
Active regeneration
In which case it should be possible to complete a regeneration cycle and clear the warning light by driving for 10 minutes or so at speeds greater than 40mph.
The easiest and cheapest method of DPF filter cleaning is by driving the vehicle for a long-distance at high revs per minute. Doing this increases the heat of the exhaust and burns the soot blocking the DPF filter. It's best to drive on a motorway or A road where you can keep the vehicle at a consistent speed.
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.
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.
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.
An automatic regen does not require any action by the driver, other than making sure the truck stays ON. It is safe to continue driving as normal. A regeneration cycle typically takes between 10 and 30 minutes to complete.
To kick off a manual DPF regeneration you should
It can take anywhere from 5 minutes to over an hour depending on how blocked the filter is.
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.
Driving at a speed greater than 40mph for more than 10 minutes should ensure your DPF goes into 'regeneration' mode and clears the blockage.
While your vehicle won't stop running the moment the light turns on, continuous driving can lead to more severe issues like decreased fuel efficiency, reduced performance, and in the worst case, engine damage. An illuminated DPF light will cause an MOT failure.
Low engine RPM
Alongside the engine not producing much power, the engine may not be able to rev very high, sometimes reaching a top RPM of 3,000. This is a consequence of both the exhaust gases restricting the engine's usual cycle, and because of the lack of turbo pressure.
There are two main types of DPF regeneration: passive and active; however, DPF regeneration can be performed manually using a scan tool. Passive DPF regeneration occurs naturally during normal driving conditions when the temperature of the exhaust gas is high enough to burn off the particulate matter.
In order for manual regeneration to occur, the driver must push the DPF switch when the vehicle is stationary with the engine running. Engine RPM will increase until the exhaust becomes hot enough to burn off the PM (soot) collected in the DPF.
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.
Once the DPF clean has been performed a regen can occur. Whenever it is necessary to perform a forced regen an engine oil change is required after the regen.