When a catalytic converter is clogged, you are likely to notice several symptoms, including a drop in your car's fuel efficiency, failure to accelerate properly and even your car not starting correctly. Many cars have dashboard lights that indicate when a catalytic converter isn't working properly. In addition, if you are required to have smog checks done on your car, a clogged catalytic converter is likely to cause you to fail the test.
Your catalytic converter is a vital part of your car's emissions control system. It is rare for a catalytic converter to fail because they are designed to last for the life of the vehicle. However, your catalytic converter sometimes clogs, usually due to a problem in another part of your fuel system. For instance, if your fuel mixture is too rich, your catalytic convert can overheat and even start to melt. If your fuel becomes contaminated or your exhaust system fails to perform correctly, you may also see symptoms indicating that your catalytic converter is clogged.
If you see the symptoms listed above, including decreased fuel economy, stalling while driving or misfiring, take your car to your mechanic to have the catalytic converter checked. It is illegal in many states to remove your catalytic converter, and your mechanic will have electronic diagnostic machines to help pinpoint exactly what is wrong with your catalytic converter.