how to unclog a catalytic converter without removing it

The catalytic converter is an integral part of the exhaust system. It belongs to vehicles solving all exhaust leaving the engine before it can be emitted to the outside environment. It uses multiple chemical reactions to turn the harmful exhaust into safe gases before they go out. However, the catalytic converter is out of order sometimes or gets clogged after a long time of usage. How to unclog a catalytic converter without removing it? Let’s find some methods!

How to find out a clogged catalytic converter

The engine accelerates slowly or it’s difficult to start. If you catch these signs, it’d be supposed that your catalytic converter is clogged. Clogs are fighting against the flow of exhaust out of the engine. When a catalytic converter is clogged, it affects the engine, preventing it from emitting the air pollutants.

Next, you can smell sulfur when your catalytic converter gets clogged. That gas is called “rotten egg” gas. It’s the formation of hydrogen sulfide (H2S). As a catalytic converter doesn’t work properly, it cannot solve pollutants and can release this gas. Moreover, ammonia (NH3) odor is also a sign of poor catalyst function.

You should notice the catalytic converter’s housing. If it is discolored or warped, an internal leakage or overheating can be happening.

Noise is a warning sign. It’s supposed to be a broken catalyst if you hear noise when starting the engine.

If you don’t have the catalytic converter tested periodically, you won’t find out problems. It’s good to conduct annual or semi-annual emissions tests to realize issues as soon as possible.

You can use vehicle warning lights to check if the catalytic converter has the issue. You focus on the illuminated check engine light or malfunction indicator lamp (CEL or MIL) to see if it shows a catalytic converter diagnostic trouble code (DTC).

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Methods to unclog a catalytic converter

“Italian Tune-Up” method

People apply this method to solve a few automotive problems which are from lack of heat. If a driver doesn’t push his vehicle hard enough to heat the catalytic converter, it can be out of order sooner.  The range of the most-efficient temperature is between 800 °F (426 °C) and 1,832 °F (1,000 °C). This method is simple to follow.

You should run a vehicle harder for several miles. The high temperature will burn off performance-robbing deposits in the cylinder head, oxygen sensors, intake, exhaust, and catalytic converter.

Fuels and Fuel Additives

You can take advantage of a useful fuel or fuel additive to unclog a catalytic converter. Select a product that can remove catalytic converter deposits. If you only use cheap low-octane fuel for your vehicle now, you can try to use some tanks of high-octane fuel.

In your next refuel, you should try to add one gallon of lacquer thinner to ten gallons of gas. This may help get rid of the accumulation of solids in the catalytic converter. Combining this method with the “Italian Tune-Up” method is a good idea.


The issue of a catalytic converter can come from engine-related problems. For example, an old oxygen sensor likely fails to warn a catalytic converter issue. A technician can check if the oxygen sensor works properly.

That fuel trim runs too lean or too rich can cause a clogged catalytic converter. Oil burning or engine misfire problems also create catalytic converter deposits. If finding out the issue soon, you will prevent your vehicle from removing its catalytic converter.

Exhaust Problem

Exhaust leakage will influence oxygen sensor readings without setting other DTCs. You need to check if your vehicle has an exhaust issue. Repair the issue immediately after you find it. After exhaust leakage is fixed, the catalytic converter gets over too. Replacing a catalytic converter is quite expensive. You can prevent this by looking for other issues and solve them as soon as possible. For example, you must determine worn exhaust gaskets and corroded flex pipes, then repair them before the catalytic converter gets broken.

Watch the video:

How to Make Your Catalytic Converter Last Longer

  • Drive your car frequently. The machine needs to be used
  • Conduct regularly scheduled maintenance
  • Consider using to high-octane fuel
  • Check engine


How to unclog a catalytic converter without removing it? You have to resolve the clogged catalytic converter before it leads to engine damage. A clogged catalytic converter doesn’t mean it’s useless. You can fix it to save your money. It’s essential to check your vehicle regularly and repair it promptly.


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