Vital Elements on the Diesel Oxidation Catalyst on the Engine

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The aftertreatment system consists of four components, also known as the diesel emissions system. It is important that anyone who performs maintenance and repairs on the diesel aftertreatment system understands how the components of the systems work. I have received questions specifically about DOC and will answer them in this article.

What does DOC mean in diesel engines?

DOC in a diesel engine stands for Diesel Oxidation Catalyst.

Understanding the Diesel Oxidation Catalyst

DOC is designed to convert carbon monoxide and hydrocarbons into carbon dioxide and water. It basically breaks down pollutants in the exhaust system of a diesel engine, which helps reduce particulates.

How it works

The exhaust flows directly through the DOC substrate with very little restriction. In the after-treatment system, there is a hydrocarbon metering system where the fuel is metered at a specific temperature; the fuel turns into steam and the steam sets off the chemical reaction that produces heat. The ECM has a thermal management system where it maintains heat and this process allows the diesel particulate filter to operate at peak performance.

Can DOC be cleaned like a diesel particulate filter?

Yes, whenever the DPF is removed for cleaning, the DOC must also be removed, inspected and cleaned. It is recommended to follow the same cleaning method as the DPF. When technicians see a DPF error code multiple times, they focus on cleaning the DPF but leave the DOC in place. This is an error because the DOC is a streaming device. Therefore, what is in the filter has passed through the DOC and it also needs to be cleaned. If the DOC is not clear, it can become clogged and this is part of a larger problem that needs to be diagnosed.

Why does a DOC fail?

DOCs are coated with precious metals and over time these deteriorate causing the DOC to fail. DOC has no moving parts, which gives it a long life cycle. Therefore, 80% of DOC and DPF failures are premature due to engine issues.

DOC has a job, which is to create heat for the oxidation of soot. But if the engine is not working properly due to bad injectors or a turbo problem, or if the aftertreatment system is not working properly due to exhaust leaks or a leaking hydrocarbon metering device , DOC will fail prematurely. We will see DOC contamination which in turn could poison DOC and cause DOC face plugging.

What is DOC facial filling?

Face plugging is an extreme build-up of carbon on the inlet side of your DOC. This extreme build-up causes additional exhaust back pressure and restricts exhaust flow, hampering the performance of the downstream DPF and SCR.

The key to after-treatment system maintenance

Whatever component of the aftertreatment system you are working on, the most important thing to remember about maintaining the aftertreatment system is: “Problems upstream of the system are often the cause of downstream failures. “

It is important to examine the entire aftertreatment system when diagnosing problems. But beyond that, it’s just as important to look at other engine systems.

Some information is taken from the Internet.

via DOC and it also needs to be cleaned. If the DOC is not clear, it can become clogged and this is part of a larger problem that needs to be diagnosed.

Why does a DOC fail?

DOCs are coated with precious metals and over time these deteriorate causing the DOC to fail. DOC has no moving parts, which gives it a long life cycle. Therefore, 80% of DOC and DPF failures are premature due to engine issues.

DOC has a job, which is to create heat for the oxidation of soot. But if the engine is not working properly due to bad injectors or a turbo problem, or if the aftertreatment system is not working properly due to exhaust leaks or a leaking hydrocarbon metering device , DOC will fail prematurely. We will see DOC contamination which in turn could poison DOC and cause DOC face plugging.

What is DOC facial filling?

Face plugging is an extreme build-up of carbon on the inlet side of your DOC. This extreme build-up causes additional exhaust back pressure and restricts exhaust flow, hampering the performance of the downstream DPF and SCR.

The key to after-treatment system maintenance

Whatever component of the aftertreatment system you are working on, the most important thing to remember about aftertreatment system maintenance is: “Problems upstream of the system are often the cause of downtime. downstream. “

It is important to examine the entire aftertreatment system when diagnosing problems. But beyond that, it’s just as important to look at other engine systems.

Some information is taken from the Internet.

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