How to Determine if the Catalytic Converter is Clogged?

[BennettMarie]

Increased fuel consumption, decreased power, and no airflow at the exhaust pipe indicate a clogged catalytic converter. Below are specific details about the severity of catalytic converter clogging: 1. Mild Clogging Stage: At this stage, chemical complexes are adsorbed on the catalyst surface, only manifesting as reduced exhaust purification efficiency and excessive emissions. Colored smoke from the exhaust pipe is often visible. 2. Moderate Clogging Stage: Chemical complexes have accumulated to a certain extent on the catalyst surface. This stage is characterized by increased exhaust backpressure, higher fuel consumption, and decreased power. The engine warning light usually comes on at this point. 3. Severe Clogging Stage: Due to significant clogging, the catalytic converter's operating temperature rises. This stage presents as a severe drop in power, frequent stalling, and in extreme cases, a red-hot exhaust pipe, unusual noises, and foul-smelling exhaust.

[DiAdelyn]

Recently, I've noticed a significant lack of power when driving. Even when I floor the accelerator, the car still feels sluggish, especially noticeable when climbing hills. The engine warning light on the dashboard frequently comes on, and an OBD scanner showed low catalytic efficiency. Fuel consumption has also increased sharply—previously, a full tank could last 500 kilometers, but now it's down to 400 kilometers before needing a refill. The exhaust pipe feels much hotter than usual, and the exhaust emits a strong sulfur smell. Considering all these symptoms together, I'm pretty sure the catalytic converter is clogged. Finally, I took it to the repair shop for confirmation, and upon opening it up, sure enough, there was a layer of carbon buildup and broken ceramic honeycomb inside.

[DelDallas]

Last time I noticed my car made strange noises when accelerating hard, like metal pieces clanging inside. At idle, the tachometer was unstable, with the needle shaking up and down noticeably. An experienced mechanic taught me a trick: after a cold start, block the exhaust pipe outlet with your hand. If you can't hold back the exhaust pressure within two or three seconds, it's normal. But I blocked it for five or six seconds without feeling significant pressure, clearly indicating poor exhaust flow. Later, the repair shop tested the exhaust backpressure, and the reading was more than double the standard value. When they removed the catalytic converter, they found the honeycomb structure was crushed, and the aluminum casing had turned blue from overheating. These real-life experiences taught me to judge clogging issues from multiple angles.

[VonPiper]

To determine if the three-way catalytic converter is clogged, I mainly look for three signs. First, sluggish acceleration, especially feeling choked after 3000 RPM. Second, revving the engine in neutral, the RPM can reach 6000 but drops back unusually slowly. Third, using an infrared thermometer to measure the temperature difference before and after the catalytic converter—normally there should be a difference of over 100°C during operation; if the temperatures are nearly the same, it indicates the converter isn't processing exhaust gases. These methods are simple and practical, allowing a preliminary check without disassembly. However, for a definitive confirmation, you need to inspect whether the honeycomb structure is cracked or clogged with carbon deposits.