National Six Torque Limiting Case (2): Dpf Blocking Fault
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National Six Torque Limiting Case (2) Dpf Blocking Fault Analysis

The implementation time of national VI emission standard is slowly approaching, and many main engine manufacturers have laid national VI products in the channel. As we all know, DPF is a necessary component in the post-treatment system of national VI diesel engine. Due to the high technical content and high cost of this system, if the DPF is blocked, it will affect the normal driving of the vehicle. Reasonable use and maintenance of DPF is an important skill for the normal use of National VI diesel engine of Dpf blocking.

What Is Dpf And What Is Its Use Of Dpf Blocking ?

DPF (particle trap) is a ceramic filter installed in the post-treatment system of diesel engine. It mainly filters the particulate matter (PM) in the exhaust emission to purify the exhaust of dpf Blocking .

Composition Of Dpf:

It is made of porous wall flow ceramic material and coated with precious metal coating, mainly including packaging, clamp, carrier and gasket of  dpf Blocking ;

Functions Of Dpf:

Its main function is to capture soot particles and other particles in diesel vehicle tail gas, so as to purify the tail gas, burn it through regeneration and generate harmless carbon dioxide. DPF can effectively purify more than 90% of particles in exhaust gas of dpf Blocking .

Why Is The Dpf Blocked

These soot particles captured by DPF will be burned inside the carrier in the form of active or passive regeneration and transformed into a small amount of ash, which is a non combustible substance and mainly consists of the chemical components of lubricating oil additives, such as calcium, sulfur, zinc and phosphorus compounds of dpf Blocking ;

The less the engine burns and the lower the quality of fuel and lubricating oil, the easier it is to produce more polymers. The salt containing lubricating oil or fuel additive elements is blocked in the DPF, and its main components are calcium salt, sulfate, zinc salt and phosphate, which leads to serious blockage of DPF and affects the normal use of vehicles of  dpf Blocking .

Hazards Of Dpf Blockage

Affect Power Performance And Fuel Consumption

With the increase of service time, more and more impurities will accumulate in the DPF, resulting in the further increase of vehicle exhaust back pressure. After the DPF is blocked, it will affect the smoothness of engine exhaust, and then affect the engine power.

High Maintenance And Replacement Costs

If the DPF fails or is damaged, it generally needs to be repaired or replaced. Among them, the price of the DPF assembly ranges from RMB 11000 to RMB 20000. If one is broken, it is enough for you to run for half a month in vain.

How To Deal With Dpf Blockage?

The particulate matter and ash captured in DPF must be treated in time to avoid serious blockage in the later stage. Under normal circumstances, DPF will regenerate according to the severity of blockage, that is, inject diesel oil into the exhaust pipe for combustion, and burn the particles at high temperature to become ash.

Generally speaking, DPF regeneration can be divided into passive regeneration and active regeneration. If the blockage is serious and the regeneration cannot meet the requirements, it needs to be removed manually.

Passive Regeneration:

During driving, if the DPF indicator light flashes, it indicates that regeneration is in progress. Generally, when the system detects that the particulate matter in the DPF device is deposited to a certain amount, the vehicle speed remains above 60km / h, and the system will regenerate and oxidize no into NO2 in doc. Since NO2 is more active than O2, it can be used to oxidize carbon particles at 250-450 ° C without manual operation Dpf Blocking .

Active Regeneration:

When the system detects that a certain amount of particulate matter has been deposited, the active regeneration cannot be handled. This is because the DPF yellow light on the vehicle instrument turns on. It is necessary to press the DPF regeneration button in the vehicle for passive regeneration, that is, the oxidation reaction occurs in doc by injecting diesel oil, which increases the exhaust temperature to more than 550 ° C, so that carbon combustion oxidation reaction generates carbon dioxide of dpf Blocking .

Regeneration Precautions:

When the regeneration indicator light is on or flashing, please stop nearby, pull up the handbrake, keep the engine idling, press the in-situ regeneration switch to regenerate the engine in-situ. The whole process takes about 30 to 45 minutes. During in-situ regeneration, the engine speed increases significantly (1500 rpm). After the engine automatically returns to idle speed, the regeneration indicator goes out and can drive normally.

If the regeneration indicator is off, turn off the engine, wait for five minutes, and then execute three consecutive ignition cycles to turn off the OBD fault indicator.

If there is no response after pressing the regeneration switch, check whether the clutch is pressed, whether the brake is pressed, whether the accelerator pedal is pressed, whether the cruise and power take-off (PTO) switch is pressed, whether the air conditioning switch is pressed, and whether the regeneration prohibition switch is pressed.

be careful:

(1) No operation on the engine is allowed during regeneration.

(2) The turbocharger makes a slight “pop” sound during regeneration. This is normal.

(3) During regeneration, keep away from gas stations and other flammable and explosive places.

Manual Removal

  1. Due to the special structure of DPF, after using for a period of time, the dry soot and organic matter on DPF will be regenerated to generate ash, which will accumulate to a certain extent and need to be removed manually.
  2. Manual removal is used for DPF carrier blockage cleaning, that is, the ceramic filter and its accessories are placed in the heating chamber and heated to 550-600c to decompose and Ashe the urea crystal and loosen other particles, and then make the high-speed air flow pass through the small holes of the ceramic filter, blast and pressure purge for many times to clean the degraded carbon ash and remove the carbon ash in the carrier, Achieve the regeneration effect of clearing blockage.

Precautions To Avoid Dpf Blockage

Card users need to pay attention to fuel, engine oil and urea solution to avoid DPF blockage.

1. Fuel oil: standard national VI fuel oil from formal channels must be used. Low grade or unqualified fuel may not only damage the fuel injector or oil pump, but also cause doc or SCR poisoning, resulting in DPF blockage;

Engine oil: engine oil of no less than ck-4 grade shall be used. Because substandard engine oil will also cause rapid blockage or failure of DPF;

3. Urea solution: Vehicle urea with a concentration of 32.5% is required for national six models. Unqualified urea solution is most likely to cause crystallization blockage of urea nozzle; If there are many crystal blocks, it will even cause SCR blockage, resulting in greater failure to the post-treatment system;


To use DPF correctly, first of all, we should refuse low-quality fuel such as small oil and low-quality engine oil urea. Secondly, in the use of DPF, we should operate in strict accordance with the specifications to reduce the occurrence of blockage as much as possible. After all, the price of PDF 10000 or 20000 is comparable to the profit of one month.

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