Troubleshooting a Clogged Catalytic Converter

A catalytic converter.

If you are troubleshooting a clogged catalytic converter, it is advisable to check over the system to diagnose the problem. If you are a novice with car engine components and their functions, you might not be aware that it isn't a normal occurrence for a catalytic converter to wear out. They are usually more subject to external damage like road impact or internal engine damage caused by overheating.

Check for Engine Misfiring

If you detect misfiring in the engine system, you can locate the cause. The catalyst can over heat due to the misfiring, or, an excessively rich fuel mixture in the engine can do the same. When an extra rich fuel mixture occurs raw fuel enters into the catalytic converter and gets ignited. This results in a melting of catalyst components.

If it is clogged, you will have to replace the entire unit because catalytic converters cannot be repaired.

Diagnosing Where the Issue Is Coming From

Finding the cause of a clogged catalytic converter can normally be traced to a fuel system problem. A typical sign of this would be a restriction in the behavior of the exhaust system caused by the melting of catalyst materials inside the converter. The catalyst material can become contaminated by silicon. Check the body of the converter for signs of wear or breakage and replace if necessary.

Is Performance Affected?

In the event that evidence points to a clogged catalytic converter you will become aware that exhaust gas gets trapped in front of the catalyst. This creates back pressure which hampers the smooth running of your engine and prevents it from breathing. This increase in back pressure could also cause your engine to stall shortly into your drive. It will behave like an air lock in the system, making the car jerk or feel that no fuel is reaching the engine when you depress the accelerator pedal.

You will also notice a serious deterioration in your fuel economy. Your vehicle will use a vast amount more fuel than you are used to and this will cost you greatly if your only fault is caused by the clogged converter. You can solve this by replacing the catalytic converter.

Oxygen Deprivation Issues

A sure way to diagnose whether a catalytic converter is clogged is to remove the oxygen sensors temporarily from the exhaust pipe. If there is an obvious change in the performance of the vehicle then you can safely reach the conclusion that the converter is clogged. As catalytic converters are not repairable, it will have to be replaced.


You may hear a whistling sound when the accelerator is applied. This indicates a restriction in exhaust flow as well as the symptoms of catalytic converter problem. You may also hear rattling noises when you vehicle is idling. They will get louder as you rev the engine or drive at high speeds. Sounds like this point to a faulty converter and therefore, again, it will need replacing.

These tips for troubleshooting your clogged catalytic converter should get your going again. Happy driving!