Borys
MB Enthusiast
Found this on other forum
Thought it will be handy
If all the OEMs gave concise, easily understood guidance about Diesel Particle Filters (DPFs) in their owner handbooks, a lot of this confusion and misinformation could be avoided.
Under normal driving conditions, and when the engine and exhaust are fully up to normal operating temperature, a certain amount of soot/particle burn-off will be occuring continuously.
This process is known as passive regeneration, and it relies purely on the catalytic material in the DPF. It will generally be more effective on cars that travel regular long distances at speed, because the exhaust will run at a higher temperature. The ECU makes no adjustments to enhance this process.
Although some burn-off is occurring continuously, there will be a net build up of soot in the filter over time. To deal with this build-up, periodic active regens are necessary. During active regens, the ECU makes adjustments to engine settings specifically designed to substantially raise the temperature in the dpf.
There are two types of active regen.
The first type of active regen will be triggered by the ECU when necessary, and when operating conditions are right for it to proceed. There will not be any explicit notice given to the driver. Although, it may be possible to infer that a regen is taking place from certain signs, e.g. rear demist active on the eco display, raised idle speed, cooling fans running at high speed etc. This type of regen will generally complete successfully in 4 - 10 minutes.
If you do become aware of this taking place, continue driving if it is possible and/or convenient. Otherwise, don't worry about it.
The second type of active regen is also triggered by the ECU when necessary, usually after several previous attempts using the first type have failed to complete. In this case, as well as adjusting the engine settings, the driver will be given an explicit warning in the form of a DIC message, a warning symbol or a code number. The actual type of warning that you see, will depend on the type/level of DIC fitted and/or the model year of the car.
If you do get a warning like this, you must continue driving, ideally at a constant speed and at an engine speed above 2000rpm. Higher rpm (2500 or so) in a lower gear will speed the process. But remember that you will still have to drive in a safe manner, obeying speed limits, traffic signs/lights etc. This type of regen will take from 10 - 20 minutes to complete.
If this process fails to complete, it will be tried again at the next opportunity. After 2 or 3 failed attempts, the ECU will put the car into service mode (limp mode), at which time it will need to be taken to a workshop for attention. A goodworkshop should check the engine for any mechanical or electronic issues that could make a regen fail or cause engine damage, before carrying out a forced regen.
A forced regen is exactly what it says. It has to be forced using diagnostic equipment, either on the road using portable equipment, or in a workshop.
Driving at a constant speed on a motorway in a lower gear will not trigger an active regen, unless the ECU has determined that a regen is actually necessary.
Thought it will be handy
If all the OEMs gave concise, easily understood guidance about Diesel Particle Filters (DPFs) in their owner handbooks, a lot of this confusion and misinformation could be avoided.
Under normal driving conditions, and when the engine and exhaust are fully up to normal operating temperature, a certain amount of soot/particle burn-off will be occuring continuously.
This process is known as passive regeneration, and it relies purely on the catalytic material in the DPF. It will generally be more effective on cars that travel regular long distances at speed, because the exhaust will run at a higher temperature. The ECU makes no adjustments to enhance this process.
Although some burn-off is occurring continuously, there will be a net build up of soot in the filter over time. To deal with this build-up, periodic active regens are necessary. During active regens, the ECU makes adjustments to engine settings specifically designed to substantially raise the temperature in the dpf.
There are two types of active regen.
The first type of active regen will be triggered by the ECU when necessary, and when operating conditions are right for it to proceed. There will not be any explicit notice given to the driver. Although, it may be possible to infer that a regen is taking place from certain signs, e.g. rear demist active on the eco display, raised idle speed, cooling fans running at high speed etc. This type of regen will generally complete successfully in 4 - 10 minutes.
If you do become aware of this taking place, continue driving if it is possible and/or convenient. Otherwise, don't worry about it.
The second type of active regen is also triggered by the ECU when necessary, usually after several previous attempts using the first type have failed to complete. In this case, as well as adjusting the engine settings, the driver will be given an explicit warning in the form of a DIC message, a warning symbol or a code number. The actual type of warning that you see, will depend on the type/level of DIC fitted and/or the model year of the car.
If you do get a warning like this, you must continue driving, ideally at a constant speed and at an engine speed above 2000rpm. Higher rpm (2500 or so) in a lower gear will speed the process. But remember that you will still have to drive in a safe manner, obeying speed limits, traffic signs/lights etc. This type of regen will take from 10 - 20 minutes to complete.
If this process fails to complete, it will be tried again at the next opportunity. After 2 or 3 failed attempts, the ECU will put the car into service mode (limp mode), at which time it will need to be taken to a workshop for attention. A goodworkshop should check the engine for any mechanical or electronic issues that could make a regen fail or cause engine damage, before carrying out a forced regen.
A forced regen is exactly what it says. It has to be forced using diagnostic equipment, either on the road using portable equipment, or in a workshop.
Driving at a constant speed on a motorway in a lower gear will not trigger an active regen, unless the ECU has determined that a regen is actually necessary.
