Removing and cleaning a diesel particulate filter (DPF) (Articles)

This article describes the function, maintenance, and cleaning of the additive-free diesel particulate filter (DPF), using the 2.0 TDI 16V PD 140PS engine as an example, specifically the engine with the code BRE. The BRE engine was installed in the Audi A4 and Audi A6.
The basic functionality and procedure for DPF cleaning are essentially the same for most other 2.0 TDI engines equipped with a diesel particulate filter.

Immediately before removing the DPF, it should be forcibly regenerated using VCDS:
Forced regeneration of the DPF on VAG TDIs

Attention: A DPF (Diesel Particulate Filter) that is inevitably contaminated during normal operation (or, more commonly, not fully regenerated) is not suitable for cleaning! During cleaning, it's not the soot itself that can be removed with water, but only the ash (which is burnt soot).

The diesel particulate filter for this engine consists of ceramic material (silicon carbide, platinum-coated), specifically interconnected tubes that form a blocked structure. Several of these blocks, in turn, form the catalytically active DPF filter element.


Required parts

6 copper-plated nuts M8, N90200201.
Dichtung für DPF-Turbolader, Teilenummer 3A0253115.
Exhaust pipe with DPF, part number 1H0253115.
Hot melt adhesive

Expansion of the diesel particulate filter

Remove the engine cover.
Remove the air intake and air filter cover (using 2 Phillips head screws located at the top of the grill).
Loosen the air intake snorkel from the air filter housing (using the hose clamp).
Remove the air filter and the lower air filter housing.
Remove the DPF from the turbocharger [SW12, M8].
Wiring the lambda sensor and temperature sensor input to bypass the DPF (Diesel Particulate Filter).
Install/replace the oxygen sensor on the DPF (Diesel Particulate Filter), and when removing the oxygen sensor, be careful not to damage the connector cable. Ideally, create a loop (180-degree bend) about 3cm after the probe, and then connect the cable directly to the probe while pulling it out.
Disconnect and reconnect the differential pressure sensor.
Remove the engine bay cover.
Loosen and slide the horizontal support for the exhaust pipe to the side.
Vertical support for exhaust pipe, loosen [SW16, M10].
Remove the DPF (Diesel Particulate Filter) from the exhaust pipe [socket size 12, M8 bolt].
Remove the AGR cooler from the cylinder head and place it to the rear.
Remove the DPF.
Remove the differential pressure sensor with its hose from the DPF (Diesel Particulate Filter).
Unscrew the temperature sensor located at the DPF inlet. Heating the threaded housing can help. Location: The sensor outlet is located centrally, towards the lambda sensor connector.

Cleaning of the DPF

In order to ensure that only ash remains in the DPF during cleaning, a forced regeneration was performed using VCDS, and immediately after its completion, the vehicle was disassembled. Ideally, you should drive the vehicle directly onto the lift with the regeneration cycle almost complete (load value < 2%) and then stop the engine. The goal of the forced regeneration performed immediately beforehand is to burn off filter components that are insoluble in water and that make cleaning more difficult, such as. Sulfur or soot, which prevent cleaning with a solvent such as water.
The regenerated DPF is then flushed with a garden hose, but in the opposite direction of the normal exhaust flow. Be careful when using pressure washers, do not direct the jet stream at individual channels!

Installation of DPF

Important: Secure sensor cables, ensure correct routing. Please ensure that the cables are kept a sufficient distance from hot parts of the exhaust system or exhaust manifold, and that any heat shields are properly positioned.
Apply high-temperature thread sealant to the M8 threads on the DPF, and use new copper M8 nuts.

Matching ash mass with VCDS

Select the engine control unit (ECU address 01), then choose the VCDS function "Adaptation/Adjustment." Enter the new ash content value into channel 12, calculation details are in the VCDS label file, see the example image below.
As a new ash mass value, I entered 4g (the DPF is practically new). In newer engine control units, utilize the function to reset the ash mass.

Values Differential pressure

A summary of which differential pressure values should be considered normal can be found in the following topic:
Normal values for differential pressure at the DPF of TDI engines

Further links, background information on diesel particulate filters.



Background information: Difference between ash and soot

Unfortunately, many readers do not distinguish between soot (carbon/carbon compounds that can be burned) and ash (combustion residues, what remains of soot, among other things).
The rumor persists that one can "burn away" the ashes or "dissolve" them with common cleaning agents. This is not like that.
Ash is essentially composed of various metal oxides and carbonates that require strong acids to partially dissolve them, acids that would have already corroded the DPF housing long before.
The obviously few owners of a simple wood-burning stove are clearly at an advantage here, because no one:roll: from that group would ever think of dissolving ash in the stove using dishwasher tablets, or of emptying the ash container with a soldering iron.
The ashtray is cleaned by emptying it. You turn it upside down and pour the contents out. That's exactly what reverse flushing the filter capillaries in the DPF does.


Chip tuning / Tuning and DPFhttp://www.mie.uth.gr/labs/ltte/pubs/PhD_Stratakis.pdf

Be careful with vehicles equipped with a DPF and poor chip tuning. While with TDIs without a DPF, the turbocharger is primarily damaged over time, with vehicles equipped with a DPF, the DPF itself can also be damaged and lose its effectiveness. Then it will be expensive.
When having a vehicle tuned, please ensure that the work is done professionally and that the exhaust temperature and soot emissions remain within normal limits. With VCDS, for example, you can observe the corresponding temperatures in real-time when driving at full throttle and draw your own conclusions about the quality of the tuning.