Catalytic Converters


Can a poorly tuned engine or an overly rich air/fuel mixture cause permanent damage to the catalytic converter?

I had one replaced only three years ago and it lasted only 34000 miles. I would like to know what can cause it to fail so soon.


It’s possible that the converter might get clogged up with soot from the condition you describe. Also, if the engine burns significant amounts of oil, that too can shorten a converter’s life since it catches much of the resulting smoke.

What’s leading you to believe this one has failed at only 34K?


I recently failed an emission test. My mechanic said the NOX was way too high. He replaced the CC that had only 34k on it. Then the car passed the emmision test


Make, model, year, mileage, history.
Does it burn oil?


1992 Buick Century. 3.3L V-6, 189000 miles. I don’t know if it burns oil. I still get the same gas mileage when I first bought it in 1995. Because I’ve had so many new parts put on the car, only the odometer has 189000 miles on it. If it does burn oil, should I switch to a heavier weight such as 10W-40 instead of the recommended 10W-30?


The EGR system was DESIGNED to lower NOx. Have a mechanic check the operation of the EGR system. The test methods are in the repair manual, such as Haynes, or Chilton,s.


I don’t know if it burns oil.

Every car owner should check their oil on a regular basis. They need to know if it starts using oil. If it is using oil then there is a good chance that killed the converter. As for your question, yes running rich can kill a converter, but as you may have guessed by now, we are not betting on it and you should not either. Making that assumption can lead to some expensive repairs that may not be needed.