Mercedes-Benz Diesel Particular Filter (DPF) may build up excessive soot content, which can lead to the exhaust restriction, and eventually, the check engine light turning on.
If you have a diesel Mercedes-Benz and have been quoted a new DPF filter, ask the mechanic to first carry out a forced DPF regeneration. In some cases, DPF regeneration may need to be carried out twice to clean a clogged DPF. Replacing the DPF is rarely required and may only be required in very rare cases. Typically DPF replacement is not needed if the vehicle has less than 200,000.
Mercedes-Benz DPF Regen Tools
With the last two scanners make sure the engine is running. The DPF regen function may be listed under the ECU > Adaptations or it may be listed under the Reset Menu available before you select the model.
How to regenerate Mercedes DPF
In this guide, we will show you how to carry out DPF regeneration with a diagnostic scanner. This is called a forced regeneration and can be performed if passive DPF regeneration has failed.
Before you start
- The vehicle will need to be driven.
- Two people required.
- DPF regeneration takes about 30 minutes.
- No other fault codes should be active except DPF - Ensure no engine related fault codes are present (they will prevent the DPF from starting)
- Ensure there is at least 20% fuel in the tank
- Risk of fire. During this procedure, the exhaust temperature is exceptionally high and can reach up to 700 °C.
Here is how to regenerate Mercedes DPF: To perform this procedure, you will need a Professional OBD-II Diagnostic Scanner that supports the DPF regeneration function. The menu names may vary slightly between scanners but the same for all scanners. Pictures are with TopDon ArtiPad, DPF regen steps the same for Mercedes Star Diagnostic C3 and C4 scanners.
- Connect your scanner to the diagnostic port under the dashboard. Start the engine and let it idle in Park.
- Power up the scanner and select the Mercedes-Benz model. Select Control Units.
- Next select Special Functions
- Select Regeneration of Diesel Particulate Filter when driving.
- Once the DPF regeneration is completed successfully, don't turn off the engine immediately. Instead, keep the engine running until the temperate sensor upstream of diesel particulate filter (B19/9) has dropped below 400 degrees Celcius.
- After DPF regeneration is done, clear the ECU and make sure no other fault codes are present.
- Test drive the vehicle for 15 minutes to ensure the check engine does not come back on. If the check engine light still comes back on
- Follow the instructions under the DPF regeneration menu.
- You will need to drive the vehicle at speeds 35mph or higher.
- Try to keep engine RPMs between 2000 and 4000. If you slow down, downshift the transition gear so that the RPMs remain in the recommended range.
- Two people are required to complete this test.
This procedure should be performed by an auto mechanic. The following video shows how Mercedes DPF regeneration is performed.
Mercedes DPF regeneration should not be performed if there are oil leaks near the exhaust system.
What is important to realize is that passive DPF regeneration is usually activated automatically periodically, but certain conditions must be met. Usually, on extended highway trips, the regeneration process takes place without the driver, even realizing. If passive DPF regeneration fails frequently and forced DPF regeneration is required often, it could be an indication of an underlying problem with the engine.
In this guide, we show you how to perform DPF regeneration on a Mercedes-Benz. The vehicle we are working on is a 2011 Mercedes-Benz R350 with the check engine light and a code for excessive soot built up on DPF. The procedure is the same for other MB vehicles including Sprinter. This vehicle was diagnosed by a Mercedes-Benz dealership, and the owner was quoted over $4000 for a new DPF.
Passive DPF Regeneration
Passive DPF regeneration is when the vehicle starts the DPF regeneration automatically while driving to burn off soot build up on the DPF.
Passive DPF regeneration only starts when certain conditions are met. Typically after you have been driving on the highway for at least 10 minutes and when no fault codes exist in the ECU. If the required conditions are not met, passive DPF regeneration will fail, which leads to excessive exhaust soot built up on the DPF.
Forced DPF Regeneration
If multiple attempts to start passive DPF regeneration fail, your mechanic may have to force DPF regeneration.
One of the most common indications that you need to regenerate the DPF filter is check engine light comes on, the vehicle may get stuck in limp mode, and a fault code indicating soot content is too high get stored in the ECU.
Symptoms of a clogged Mercedes Diesel Particulate Filter (DPF) with high exhaust soot content include:
- Check engine light on
- Loss of power
- Limp mode
- A decrease in fuel economy
- No throttle response
- Car struggles to start
- Failed emission test
A variation of the following fault code may also be stored in the ECU:
- P243609 - The soot content of the diesel particulate filter is not ok or too high. There is a component fault.
What are the symptoms of a clogged DPF filter?
The first thing that you will notice if there is a problem with the DPF filter is that the check engine light comes on.
At this point, DPF regeneration failed to start automatically, usually because of too many short trips. A mechanic can follow the instructions below to carry DPF regeneration.
In some cases, if DPF regeneration was not started for an extended period, the vehicle may go in limp mode.
Do I need to carry DPF regeneration myself?
Yes, but you need a professional scanner that is able to start DPF regeneration.
Can I remove the DPF system?
Several aftermarket kits allow you to manipulate the Engine Control Unit and remove the Diesel Particulate Filter and, in some cases, the whole BlueTec system.
You may even find a company that will remove the DPF. Removing the diesel particulate filter is not legal in most countries. Vehicles with no DPF have much higher harmful emissions.
While removing a Mercedes DPF filter is illegal in most countries, cleaning the DPF system is entirely legal and a more cost-effective alternative to replacing the DPF. Many companies offer DPF cleaning service, and a quick search should reveal a few places near you. DPF cleaning is typical for trucks, but the same procedure can be performed on diesel Mercedes-Benz vehicles.