How long should a catalytic converter last?

On average, catalytic converters should last up to ten years, but this can vary according to mileage driven and engine tune. You may prefer to go by an average of 50,000 miles before you should expect to be replacing your catalytic converter. Many people can expect to replace the catalytic converter at least once during the lifetime of the vehicle if you intended to keep it for a good few years.

Failure can some times happen early, and if this occurs to you, it would be sensible to to locate and fix the cause of the root problem before paying out for a replacement CAT just in case the same should happen to you again.

Most mechanics will tell you that there are three possible ways for a catalytic converter to fail:

Melt down: This happens when unburned fuel ignites on contact when entering the catalyst. The heat generated is so intense that it literally melts the component. There are a number reasons why this could occur, including ignition/fuel injection faults, poor ignition timing, defective or worn out spark plugs, faulty oxygen sensor, and incorrect fuel mixture.

Carbon deposits: Deposits can build up on the matrix through antifreeze or oil entering the combustion chamber. This can lead to increased back pressure causing poor performance and overheating.

Catalyst fracture: Excessive vibration or external impact can cause the fragile ceramic matrix to break apart. This causes overheating and back-pressure to build up as a result.