Do you have a failing DPF pressure sensor that you’d like to temporarily bypass? Do you want to know if this is possible and how to do it? You’ve come to the right place, because we have researched these questions and have the answers for you.
Bypassing a DPF pressure sensor can be done by disconnecting the two silicone tubes from the sensor. You should leave the wire harness on the DPF sensor.
We'll talk more about the process of bypassing a DPF pressure sensor in the succeeding sections. Read on to learn whether it is a good idea to bypass a DPF pressure sensor.
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What Is A DPF?
A DPF (diesel particulate filter) is part of the exhaust treatment system in modern vehicles with diesel engines. Exhaust gases from the engine go through the DPF.
The DPF is responsible for capturing soot. This helps clean the exhaust gases coming out of a diesel-powered vehicle.
You can find the DPF near the engine, where it can capture the exhaust gases.
Most DPFs are made from a ceramic material that catalytic converters use as support. Below are the different materials that make up the particulate filter inside the DPF.
Cordierite Wall Flow Filter
Cordierite is a natural mineral that contains iron, aluminum, magnesium, and silicon. Tin mines are the most common places where you find this mineral.
In 1970, scientists developed a synthetic version of the mineral that doesn’t have iron. Exposure to high and low temperatures will barely expand or contract the synthetic version of the mineral.
This makes it highly resistant to thermal shock and an ideal material for the filtration of exhaust gases.
The disadvantage of using synthetic cordierite is that it is known to melt during the filter regeneration process.
The filter regeneration process takes longer if there are more particulates caught in the cordierite filter. Longer filter regeneration exposes the cordierite to high temperatures longer that can melt it.
This becomes more problematic if the automobile is using a passive system where the car owner needs to drive the vehicle at a certain RPM and for a certain amount of time. Soot can accumulate more in a purely passive system.
Cordierite melting is less of a problem in active systems where the car’s computer determines if there is a need to activate filter regeneration.
If the vehicle is running at a lower RPM, the temperature of the exhaust will not be enough to regenerate the filter. In this situation, the vehicle’s computer will release specific amounts of fuel into the exhaust to facilitate filter regeneration.
The major advantage of a cordierite filter is that it is inexpensive to manufacture.
Silicon Carbide Wall Flow Filter
Silicon carbide is also known as carborundum. Natural silicon carbide has been found in nature from fallen meteorites and is known as moissanite.
Silicon carbide is a very hard material. Some of its industrial applications include ceramic plates, abrasive layers, crucibles for high-temperature applications, and ceramic plates in ballistic vests.
Manufacturing plants make wall filters from sintering grains of silicon carbide.
The process of sintering uses high pressure and heat to create a solid material without melting the grains. The particles of materials in sintering will fuse to create a single solid material.
Carborundum has a higher melting point than cordierite. However, it is not as thermally stable.
Manufacturing a DPF from carborundum includes surrounding it with material that will absorb the expansion of the carborundum during high-temperature exposures.
Ceramic Fiber Filter
Ceramic fibers are synthetic materials. Silica and alumina are the main components of ceramic fibers.
These fibers are often used to make blankets, boards, and semi-rigid boards. Since ceramic fibers are less rigid than carborundum or cordierite, a ceramic fiber filter has less back pressure than wall flow filters.
A ceramic fiber filter can remove all particulates in the exhaust.
Metal Fiber Flow-Through Filters
This type of particulate filter is similar to ceramic fiber. It has the unique advantage of having the ability to introduce electrical current to the filter. The introduction of electricity creates heat that initiates filter regeneration.
Filter regeneration through electricity allows the initiation of the regeneration process even at low exhaust temperatures or low exhaust flow rates.
What Is Filter Regeneration?
The DPF captures the soot in the exhaust gases and prevents it from escaping. This significantly reduces the amount of soot that escapes through the exhaust. The wall of a DPF will allow gaseous exhaust to pass through but not particulates like soot.
Soot is the byproduct of incomplete combustion inside your diesel engine. It is made mostly of carbon.
However, soot is a solid particulate material, and it can easily accumulate inside the DPF. Once soot accumulates inside the DPF, it will start to block the flow of exhaust.
This situation is the same in all types of filters, which is why you need to replace them regularly. The difference between DPF and the other filters inside your car is that it has a filter regeneration system.
Filter regeneration uses the temperature build-up inside the exhaust system to burn up soot. Burning soot will change it to carbon dioxide—a gas that can pass through the filter substrate of the DPF.
However, burning soot requires high temperatures and a catalyst.
When you drive your diesel vehicle certain distances and under specific loads, the temperature of the exhaust gets high enough to burn off the soot and cause it to react to the catalyst. However, this is not always the case.
Short trips and low loads will not generate the temperature that the DPF needs to burn off the soot buildup.
What Does A DPF Sensor Do?
This is where the DPF differential pressure sensor comes in.
The DPF monitors pressure differences and can send a signal to initiate active filter regeneration.
In this type of regeneration, the system will add a small amount of fuel to the soot. The fuel is then burned with the soot to achieve the temperature that the soot needs to catalyze and turn into gas that can pass through the DPF.
Once all the soot inside the DPF burns away, it will be able to function normally again, and the pressure will be even.
Bypassing The DPF Sensor
The DPF sensor has a silicone hose that goes to the exhaust line before the exhaust gases reach the DPF. A second silicone hose goes to the exhaust line after the DPF.
The DPF compares the pressure coming from these two silicone lines. If the pressure difference is high, the DPF will send a signal to the PCM (powertrain control module) to initiate the filter regeneration process.
A large difference in pressure means that the volume of exhaust going out of the DPF is much less than the volume of exhaust going in.
If the system does not initiate filter regeneration, the blockage will continue to get worse, and there will be a build-up of exhaust pressure.
If you bypass the DPF pressure sensor, the DPF will keep accumulating soot without going through the filter regeneration process. Once soot fills the filter, there will be a lower flow of exhaust.
This can lead to high engine temperature, high transmission temperature, sudden sluggish engine performance, and a sharp reduction in fuel economy.
The backpressure will increase and cause soot to travel back into the combustion chamber. When this happens, soot will mix with the engine oil.
Soot is an abrasive material. If it mixes with the engine oil, soot will accelerate the wear of the engine bearings. This leads to costly repairs and the potential to damage the engine irreversibly.
Why Bypass The DPF Sensor?
Vehicle owners normally bypass the DPF sensor as part of the process of deleting the DPF system. Once you remove the DPF system, the DPF sensor will no longer be doing anything.
However, bypassing the DPF sensor alone doesn’t provide any advantage.
A failing DPF pressure sensor will activate the Check Engine light. However, it will not do anything else. It will no longer monitor the difference in pressure of exhaust gases that go through the DPF system.
Bypassing the DPF system has some benefits. However, deleting the DPF system may be illegal in your area. So, check with your local DMV to find out if removing the DPF is illegal.
There are benefits to deleting the DPF system. Avoiding the repair and maintenance cost of the DPF system is only one of them.
Keep in mind, however, that deleting the DPF can also cost a lot. You will need to reprogram the vehicle’s computer so that it will no longer throw an error for not detecting the components of the DPF system, like the DPF sensor.
Moreover, the DPF system is a part of a larger exhaust treatment system known as the EGR (Exhaust Gas Recirculation).
The EGR reintroduces small amounts of exhaust into the combustion chamber to reduce the amount of NOx in the exhaust gases that come out of the engine.
It is possible to bypass the DPF sensor. However, a better question is, why would anyone want to bypass it?
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