The catalytic converter is one of the most important parts of your vehicle’s emissions system. It works by filtering and converting harmful gases into safer ones before they exit through the exhaust. When it’s working properly, you won’t even notice it. But when it becomes clogged or fails, it affects everything from performance to fuel economy.

A clogged catalytic converter can cause symptoms that are easy to mistake for other problems, such as misfires, power loss, or even a check engine light. Knowing the signs can help you catch the issue early and avoid more serious damage to your engine or exhaust system.

What Does the Catalytic Converter Do

Your catalytic converter is part of the exhaust system. It uses chemical reactions to reduce harmful gases like carbon monoxide, hydrocarbons, and nitrogen oxides. These gases pass through a honeycomb-shaped ceramic interior coated with precious metals that help trigger those reactions.

Over time, the converter can become clogged with carbon deposits or suffer internal damage from heat, misfires, or contaminants. When that happens, exhaust flow is restricted, and the engine may struggle to perform the way it should.

Sign 1: Noticeable Loss of Power

One of the most common signs of a clogged catalytic converter is a drop in engine performance. You may notice that the vehicle feels sluggish, especially when accelerating or going uphill. This happens because the exhaust gases can’t exit the engine efficiently, creating backpressure that limits power.

If your car feels like it’s working harder than usual or hesitating when you press the gas, it may be time to inspect the converter.

Sign 2: Poor Fuel Economy

A clogged catalytic converter can throw off your engine’s air-fuel balance, causing it to run less efficiently. You may find yourself filling up more often, even though your driving habits haven’t changed.

In some cases, your vehicle may switch to a rich fuel mixture in an attempt to compensate, which only makes the problem worse. If your MPG drops noticeably, it could be more than just tire pressure or old spark plugs.

Sign 3: Rotten Egg Smell from the Exhaust

If you catch a sulfur or rotten egg odor while the engine is running, that’s a strong indicator of catalytic converter trouble. This smell comes from hydrogen sulfide, a byproduct of fuel combustion. Normally, the converter neutralizes it, but when it’s clogged or failing, the gas may pass through untreated.

The odor might be faint at first, but it usually gets worse over time and may be more noticeable when idling or in traffic.

Sign 4: Check Engine Light Is On

Your vehicle’s onboard diagnostic system monitors the performance of the catalytic converter using oxygen sensors. If these sensors detect that emissions are not being reduced properly, the check engine light will come on.

In some cases, you might get a specific trouble code like P0420, which indicates the catalytic converter is not operating efficiently. While the light could signal many things, a failing converter is one of the most common reasons it appears, especially if combined with other symptoms.

Sign 5: Rattling Noises from Under the Vehicle

If the internal ceramic material inside the catalytic converter breaks apart due to overheating or age, it may begin to rattle. You might hear this noise during startup or when revving the engine. The sound usually comes from the area beneath the car and can get louder over time.

Rattling often means the converter has experienced physical damage or is breaking down internally. In this case, replacement is usually the only option.

Can a Clogged Catalytic Converter Be Cleaned

There are fuel additives marketed as catalytic converter cleaners, but they rarely fix major clogs. Once the internal pathways are blocked or the catalyst material is damaged, cleaning will not restore full function.

The most reliable fix is to replace the catalytic converter. In some cases, the problem may be caused by another issue, like unburned fuel from a misfiring engine or oil contamination. Addressing the root cause is essential to prevent future failures.

Have Your Exhaust System Inspected at Barsh Auto in Conroe and New Waverly, TX

If your car feels sluggish, your fuel economy has dropped, or you smell something unusual from the exhaust, your catalytic converter may be clogged. At Barsh Auto in Conroe and New Waverly, TX, we provide complete exhaust system inspections and catalytic converter replacements. Our team will diagnose the problem accurately and get you back on the road with a vehicle that runs clean and smooth.

Schedule your visit today and let us keep your engine performing its best.