Diesel Oxidation Catalyst: What It Does and How It Works

The diesel oxidation catalyst is an integral part of modern diesel engines. This blog post will discuss what this catalyst does, how it works, and some common myths.

What is Diesel Oxidation Catalyst?

The diesel oxidation catalyst, or DOC, is a device fitted to the exhaust system of a diesel engine. It helps reduce NOx emissions by breaking down the unburnt fuel particles into harmless gases.

How does Diesel Oxidation Catalyst work?

The DOC uses a catalyst such as platinum or palladium to break down the unburnt fuel particles into nitrogen and carbon dioxide. The nitrogen gas then combines with oxygen in the atmosphere to create harmless nitric oxide (NO). Finally, the carbon dioxide gas is released into the air.

What are some common myths about Diesel Oxidation Catalyst?

There are many myths about the diesel oxidation catalyst, but here are two of the most common ones:

– The DOC only works when you are driving your vehicle

– The DOC will damage the engine if it is left in for too long.

The diesel oxidation catalyst only works while the engine is running but does not require any input from the driver or other people to make this happen. It also won’t cause any harm to the engine. However, if there are significant levels of carbon build-up on top of it, that can reduce its effectiveness and lead to higher emissions being released into the environment. This would need professional attention by a service technician who has access to parts suitable for removing these deposits.

– It is not possible to increase the diesel oxidation catalyst’s effectiveness.

– The DOC can be damaged by regular driving on short trips that do not allow sufficient time to reach operating temperatures.

It is impossible for anyone but a service technician who has access to suitable parts and equipment, such as carbon deposits removal tools, which are required in some cases where there are significant levels of build-up on top of the cylinder head – this will reduce its effectiveness.

Regular driving with short running hours (idling) may lead to more damage than benefits if you try increasing its efficiency because it needs certain conditions like reaching the suitable temperature range before unleashing all of its power; however, these damages won’t affect your engine but simply make it work less efficiently than it should.


There are many good things about diesel oxidation catalyst, which you must know in order to get the best and desired results.

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