Clogged Catalytic Converter Symptoms

Are there some common clogged catalytic converter symptoms? Your car is sort of like your body in that it will begin to let you know when something is wrong. That is if you listen, you’ll be able to figure out what is wrong with it. The car is the same way, if you listen to it, it will tell you some of the symptoms of clogged catalytic converter.


Any object such as a machine or an instrument, however sturdy, breaks down if it is made to operate beyond its tolerance level. A catalytic converter, which cleans the fumes of pollutants, is built to operate at pretty high temperatures. However, when it gets bad or clogged, it starts affecting the performance of the vehicle, which an astute car driver can easily notice.



One of the most noticeable and frequent of all the symptoms is a lack of power. The cat is part of the car’s exhaust system and when there is not a free flow it will get backed up which will make the car lose its normal level of power.


The catalytic converter is a component of the exhaust system and must be kept free-flowing to allow the easy passage of exhaust. When a converter becomes clogged with debris or are broken, the engine has to work much harder to accelerate and idle because the exhaust pressure is backing up in the pipe. This causes a highly erratic idle and or stalling and little or no power on acceleration, as well as higher engine temperatures. If your vehicle suddenly seems to lose more than half its power, the catalytic converter could be the culprit.




When debris or gunk is clogging up the catalyst, it will cause pressure to back up in the exhaust pipe. This will mean that the engine has to work harder when it is accelerating or idling. A common sign that there is a problem is if the car loses power suddenly, especially when you are trying to get it to accelerate like passing another vehicle or trying to get on the freeway.


Symptoms of a clogged catalytic converter include a loss of power. Because an engine is aspirated and must breath, if the restriction is severe enough the engine may not run. The technician in this question uses a vacuum gauge to confirm an exhaust restriction. If the needle on the gauge drops steadily at 2500 RPM check the exhaust for a restriction. This will likely be a clogged catalytic converter.



Another very common symptom of a cat that is blocked up is the gas mileage of the vehicle will suddenly get noticeably worse. It’s kind of like when we drink out of a large straw, and then go down to a smaller sized one. We get a lot less volume and we have to work harder to do so. When the cat is blocked up the engine will try to force all the exhaust through holes that are much smaller and it will cause the vehicle to get les miles per gallon.


Because a clogged catalytic converter makes the engine work much harder, gas mileage can decrease substantially. With that much pressure in the exhaust, it is like the difference between blowing out of a drinking straw or a 2-inch pipe. When the catalytic converter is clogged, the engine is trying to force all the exhaust out of a much smaller hole, in essence, which adversely affects the miles per gallon the vehicle will achieve.



Sometimes when there is a clog or block in the cat, it is actually one that is broken. The insides are made as a honeycomb-shaped structure that helps in heating up the fumes from the exhaust. The honeycomb shaped insides can become brittle over time and they can crack or even break off in the chamber of the cat. This can cause a lot of noises to come from the exhaust system. If the honeycomb structure has pieces that are broken off, it may also begin to rattle, especially if you shake it with your hand.


Another symptom is rattling. If you strike the bottom of the Catalytic Converter wil a rubber hammer you will hear rattling from inside the converter. That indicates that the honeycomb matrix inside the coverter has broken apart. 



These three things are the most common signs that there are something going on inside the catalyst. Poor fuel efficiency, strange noises and lack of power are the main symptoms for your bad catalytic converter.