Mercedes Diesel Particulate Filter (DPF) Problems | Cleaning | Regeneration

Are you having problems with your Mercedes Diesel Particulate Filter (DPF)? Maybe your local mechanic or even Mercedes dealer is quoting you $4000+ for a DPF replacement. In this article, you will learn more about DPF and possible fixes without having to replace it. Take a few minutes to read this article before you spend several thousand dollars on a new DPF filter. 

Symptoms

This is a list of symptoms you may notice when there are issues with the DPF. 

  • Check Engine Light On
  • The vehicle goes into limp mode 
  • Reduced speeds. 
  • Poor acceleration
  • No throttle response
  • A decrease in fuel efficiency

Problem 

mercedes sprinter diesel particulate filter

Your Mercedes check engine light comes on with one or more codes related to the DPF filter soot content being too high. These fault codes affect many 2010 and newer Mercedes models including E S GL ML R G Bluetec versions.  On Sprinter vans, throttle response is very poor and there is hardly any acceleration no matter how hard you press the gas pedal. Vehicle speed may be limited to 40 mph. 

When scanned with a generic OBD2 scanner an owner will get generic fault codes. If a professional diagnostic scanner is used such as Mercedes Star Diagnostics or Autel MaxiDAS you will get the following error: 

  • 11A700 Diesel particulate filter - The soot content of the particulate filter is too high for regeneration. 
  • 11AF00 Diesel particulate filter - The soot content of the particulate filter is too high for regeneration. 
  • P244B    Diesel particulate filter (DPF) - differential pressure too high
  • P2458 Diesel Particulate Filter Regeneration Duration
  • P2463 Diesel Particulate Filter Restriction – Soot Accumulation
Other Possible Codes
  • P1471Diesel particulate filter (bank 1) regeneration not completed
  • P2002 Diesel particulate filter (bank 1) efficiency below threshold
  • P2003 Diesel particulate filter (bank 1) particulate mass too high
  • P242F Diesel particulate filter (bank 1) regeneration not active
  • P244A Particulate filter differential pressure too low
  • P224B Particulate filter differential pressure too high
  • P2452 Particulate filter differential pressure sensor malfunction
  • P2453 Diesel particulate filter differential pressure - sensor malfunction
  • P2454 Diesel particulate filter differential pressure - sensor voltage too low
  • P2455 Diesel particulate filter differential pressure - sensor malfunction
  • P2458 Particulate filter regeneration maximum regeneration time exceeded
  • P2459 Particulate filter regeneration, regeneration frequency implausible 

 

Just because you are getting an error code "Mercedes Diesel Particulate Filter The soot content of the particulate filter is too high for regeneration" it does not mean that the DPF needs to be replaced. 

If you are having this problem don't rush into replacing the DPF filter. A DPF fault code doesn't always mean you need to replace the Diesel Particulate Filter (DPF), a repair that can run from $4000 to $6000. This problem is often fixed by manually forcing a DPF regeneration.  

Ask your Mercedes-Benz dealer or mechanic to manually carry out a forced DPF regeneration. If you have a professional scanner, you could potentially carry DPF regeneration yourself. Make sure to follow all the instructions your scanner displays before it starts DPF regeneration. 

What is DPF Regeneration

During the regeneration process, the soot that has built up inside the DPF is removed. This is done by allowing the DPF (catalytic converter) to reach temperatures up to 600 C. This allows the soot to burn up and be pushed out with the exhaust gasses.  This process is done passively or can be a forced regeneration. 

Passive Regeneration

Your Mercedes will automatically start the regeneration process while you are driving without you even knowing. 
Unless the check engine light is on for another reason or certain criteria are not met, which can cause the regeneration process to never be completed. 

If the regeneration process does not start on its own, you will eventually get too much soot built up, that one or more of the codes mentioned above will be triggered. 

Forced DPF Regeneration 

MANUAL DPF REGENERTATION

You can force Mercedes DPF regeneration with a professional diagnostic scanner such as Mercedes Star Diagnostic. Regeneration can be carried out with the vehicle driving or running but parked.

During this process, certain conditions must be met and the engine RPMs will be kept at 2000 for approximately 30 min. The procedure must be initiated by the scanner. 

There are several conditions that need to be met some of which include: 

  • Engine coolant need to reach the normal operating temperature
  • Catalytic converter needs to be over 200C as a starting point
  • Turn on lights and rear defroster
  • Set climate control to blow at max speed 
  • Hood needs to be closed

These are only a few of the conditions as they vary between models. The scanner that you will be using will display all the steps you need to follow to carry manual DPF regeneration. 

On most scanners, DPF regeneration can be started by going to:

  1. Control Units >
  2. CDI Module >
  3. Activation / Tests / Adaptations >
  4. Manual DPF regeneration

Manual Mercedes DPF regeneration takes from 30 to 50 min. During this time the DPF temperature reaches up to 600C. 

Once the process has been successfully completed, the codes above will change from Current to Stored status. This will allow you to clear the codes, which you cound't before DPF regeneration. 
Once you clear the codes, your Mercedes E R ML GL S Sprinter 320 350 2500 3500 should be out of limp mode and drive without any restrictions.  

Why wasn't passive regeneration not completed? 

Because the diesel soot particles in the DPF are not being burnt off at high temperatures. Typically because the vehicle is not doing enough highway miles or are driving too frequently in city. Another possibility is that the check engine light is on for another problem which automatically passive DPF regeneration. 

DPF Cleaning 

If the DPF is excessively blocked, with soot and ash then a professional clean or a replacement DPF will be required.

A DPF can be cleaned by removing the upstream DPF sensor and spraying fluid to clean the build up inside the DPF. This is an alternative solution to replacing the DPF. 

The following video shows you how to clean a DPF filter. A popular product is LIQUI MOLY Diesel Particulate Filter Cleaner

Frequently Asked Questions

What is the purpose of the diesel particulate filter?

To reduce particulate emissions. 

What can prevent passive DPF regeneration? 

Any fault in the ECU that has triggered the check engine light will prevent regeneration from automatically happening. Short trips. 

When do I need to replace the DPF? 

If the DPF is excessively blocked, with soot and ash then a professional clean or a replacement unit will be required.

Are DPF filter and catalytic converter the same? 

Yes and no. DPF is used in diesel vehicles.  DPF is to diesel vehicles what catalytic converter is to a gasoline engine. They are slightly different in the way that they work. 

How often do I need to carry DPF regeneration? 

It can be as early as 60,000 miles or even up to 300,000. There is no set limit because your vehicle should carry out passive DPF regeneration at random times as you drive. The only times that forced DPF regeneration is required is when the passible DPF regeneration could not be started automatically. 

Additional Resources

  1. https://roadstars.mercedes-benz.com/en_GB/magazine/route/01-2014/success-stories-cleaning-the-diesel-particulate-filter.html
  2. http://www.ceramex.com/images/Ceramex%20DPF%20Technical%20&%20Diagnostical%20Information%20.pdf

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