Reasons for catalytic converter failure.

A catalytic converter should never fail!
If it does, then there is a problem will not be fixed by simply replacing the converter. The fact that it failed is the result of a less apparent problem under the hood. If your catalytic converter needs replacing, then one of the problems listed below most likely contributed to its failure.
Here is an example of catalyst in different stages of damage (or lack of).

Engine Tune-up
A number of problems could occur to the catalytic converter as a result of an engine that is out of tune. Any time that an engine is operating outside of proper specifications; your converter suffers unnecessary wear and damage, as well as your engine.  The damage is often the result of an incorrect fuel/air mixture, incorrect timing, or misfiring plugs. Any of these conditions could lead to catalytic converter failure or worse.

Excess Fuel Entering Exhaust
The fuel that powers your vehicle is meant to burn IN THE COMBUSTION CHAMBER ONLY. Any fuel that leaves the combustion chamber unburned will enter the exhaust system and “light off” when it reaches the converter. This can “superheat” the converter to temperatures far above normal operating conditions and cause a CONVERTER MELTDOWN.
This is an example of a converter meltdown. The converter was super-heated due to a raw fuel condition in the exhaust flow. The excess unburned fuel ignited when it struck the hot ceramic catalyst and drove the temperature far above the normal operating condition of the converter. The ceramic catalyst is unable to withstand the extremely high temperature and begins to melt. The ceramic collapses and the converter is destroyed. The melted ceramic may block the exhaust flow and cause additional damage to the engine. A converter glowing red-hot or evidence of heat discoloration confirms this situation. The too-rich condition that led to this converter melt down could be the result of a number of malfunctions including faulty oxygen sensor, an incorrect fuel mixture, worn spark plugs or plug wires, a faulty check valve, incorrect ignition timing, sticking float, faulty fuel injectors or other ignition malfunctions.

Oil or Antifreeze Entering Exhaust.
Oil or Antifreeze entering the exhaust system can block the air passages by creating heavy carbon soot that coats the ceramic catalyst. These heavy Carbon Deposits create two problems. First, the carbon deposits prevent the catalytic converter from reducing harmful emission in the exhaust flow. And second, the carbon deposits clog the pores in the ceramic catalyst and block exhaust flow, increasing backpressure and causing heat and exhaust to back up into the engine compartment. Your engine may actually draw burnt exhaust gasses back into the combustion chamber and dilute the efficiency of the next burn cycle. The result is a loss of power and overheated engine components. Possible causes are worn piston rings, faulty valve seals, failed gaskets or warped engine components.

Deteriorated Spark Plug & Spark Plug Wires.
Spark plugs that don't fire or misfire cause unburned fuel to enter the exhaust system. The unburned fuel ignites inside the converter and could result in a partial or complete melt down of the ceramic catalyst. Spark plugs and spark plug wires should be checked regularly and replaced if damaged or if wires are worn or cracked.

Oxygen Sensor Not Functioning Properly.
An oxygen sensor failure can lead to incorrect readings of exhaust gasses. The faulty sensor can cause a too rich or too lean condition. Too rich and the catalyst can melt down. Too lean and the converter is unable to convert the hydrocarbons into safe elements and may not pass a state inspection.

Road Damage or Broken Hangers.
The ceramic catalyst inside a catalytic converter is made from a lightweight, thin-walled, fragile material. It is protected by a dense, insulating mat. This mat holds the catalyst in place and provides moderate protection against damage. However, rock or road debris striking the converter or improper or broken exhaust system support can cause a Catalyst Fracture. Once the ceramic catalyst is fractured, the broken pieces become loose and rattle around and break up into smaller pieces. Flow is interrupted and backpressure in the exhaust system increases; this leads to heat build up and loss of power. Possible causes of a catalyst fracture are road debris striking the converter, loose or broken hangers, potholes or off-road driving.

After You Install  A New Catalytic Converter, if your car caused the OEM catalytic converter to fail, it could cause The New Converter To Fail as well. And the warranty that comes with a new replacement catalytic converter does not cover the type of damage listed above.

A fine up to $2,500.00 can be assessed for removing or tampering with a properly functioning catalytic converter.

Bear River Converters
We are the catalytic converter experts!
Selling superior quality converters, flex pipe, and stainless tips.
Check out our eBay store!

We carry an extensive line of premium quality converters. If you need a converter, we will get it for you!
This guide was written by Bear River Converters, the catalytic converter experts. To find a complete line of premium quality converters, flex pipe, and stainless steel tips, visit our eBay store here.
To contact us:
Bear River Converters
1877 W. Park Avenue
Riverton, UT 84065

Phone: 888-782-8825 (Toll Free)
Fax: 801-446-4511
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