Most DPFs will automatically clear as they're used but on rare occasions, in specific circumstances, they may get blocked and require manual cleaning. In normal use, a DPF cleans or regenerates itself by reaching a sufficient temperature to burn off the excess soot.
During normal working condition the diesel particle filter will clean itself regularly by self-regeneration. After each regeneration-cycle, some ash are left in the filter and cause shorter regeneration interval. This means that each DPF will need service sooner or later.
Passive regeneration
So it is advised that drivers regularly give their diesel vehicle a good 30 to 50 minute run at sustained speed on a motorway or A-road to help clear the filter.
DPF active regeneration
Active regeneration happens when extra fuel is injected automatically as the filter reaches an approximately 45% full limit. The extra fuel raises the temperature of the exhaust and burns off the stored soot. Yet the journey has to be long enough to complete a full cycle.
Blocked DPFs wreak havoc with the delicate balance of your engine by preventing the normal venting of gases, which causes a variety of engine issues, as described above. In addition to reduced power and fuel efficiency, a blocked filter may eventually cause a dangerous mechanical malfunction and break your engine.
You should take your car on a run to allow the regeneration process to take place. Most engine management systems will actively regenerate the DPF when the car is driven at speeds above 40mph for around 10 to 15 minutes.
Engine Low on power. Engine cannot rev to high RPMS. Black smoke from exhaust upon acceleration. Odour of diesel fuel into the cabin.
Active regeneration will be initiated every 300 miles or so depending on how you use your car and will take 5 to 10 minutes to complete. But it's a problem if your journey's too short and the regeneration doesn't finish. During active regeneration you may notice: Cooling fans running.
The active regeneration of the particulate filter occurs when the soot level in the DPF is around 40-45 % of its capacity. When the soot reaches this percentage, afterburner fuel is injected to increase the exhaust temperature.
How to unblock a DPF? 1) DPF Regeneration - Find a motorway near you where you can drive at 70+ MPH for 30-45 minutes; this should provide the optimal conditions for the regeneration process to complete. If this works, consider a regular drive along a motorway regularly to allow the regeneration process to complete.
Technically yes, but we would not recommend it. If you ignore the DPF light and continue driving, the build-up of soot will soon reach a point whereby your car has to enter 'limp-home' mode in order to prevent any damage to the engine.
One final consideration, it takes time for a DPF to block, sometimes years. Once blocked though, turbo failure can occur very quickly.
So how do you tell that your engine is performing an active DPF regeneration? One signal to look for is your cooling fans running at a higher capacity than normal, or the sound of your engine may change note. Sometimes, a hot and pungent smell can also start coming from your engine as the soot is being burned away.
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.
If your car has an automatic transmission, shift your gears in a manual mode by moving the gear shift gently. No need to use the speed limiter, it is with no seeming value added. Ride like this for a minimum of 30 minutes. This will initiate a regeneration cycle, and your DPF will be cleaned.
A blocked DPF or obstructed exhaust will force your engine to work harder to expel exhaust gases, reducing available power and increasing fuel consumption.
The most common reasons for DPF blockages are: Short journeys where the engine doesn't reach optimum operating temperature; Clogged EGR Valve increasing diesel soot passed to the DPF; Faulty fuel injectors sending too much fuel to the air/fuel mixture; Incorrect engine oil upon servicing the car ; Turbocharger failure ...
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.
You should be able to feel the overall power increase of your vehicle. However, when the turbocharger starts to fail, you'll notice that accelerating becomes sluggish, and your car will lack the power it had before.
A maintained DPF is capable of 200,000 + kms before removal for correct cleaning or replacement.
Every diesel with a DPF has the potential for problems, however, and it all comes down to your driving style. As we said, diesels aren't suitable for just being used around town – they need longer drives too.