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Catalytic Converter Replacement

What is a Catalytic Converter?

A catalytic converter is a U.S. federal-mandated emission device that is incorporated into the exhaust system of all modern automobiles. The converter’s purpose is to lower the three main causes of pollution produced through combustion ­— carbon monoxide, nitrous oxide, and hydrocarbons (unburnt fuel). The toxic exhaust passes through a series of heated screens or honeycombs, which are coated with precious metals. These heated metals act as a catalyst that precipitate a chemical reaction, turning hydrocarbons into carbon dioxide and water, carbon monoxide into carbon dioxide, and nitrous oxide back into nitrogen and oxygen

What are the main causes of catalytic converter failure?

There are two primary causes of catalytic failure:

  1. First, over time, the additives in many of the fluids that are used in a car ­ including gasoline, engine oil, and coolant­ end up in the exhaust stream through increasing inefficiency or leaks. These additives react with the converter metals, eventually coating the screens or honeycombs to the point where the reaction becomes ineffectual.
  2. Second, and far more common, catalytic failure results directly from a poorly running engine — and this may even happen to rather new cars and trucks. When a spark plug or fuel injector functions poorly, more hydrocarbons (unburnt fuel) enters the exhaust stream. These hydrocarbons ignite on the converter screens, raising the temperature until the metal substrate melts.

What are the symptoms of a faulty catalytic converter?

The onboard computer monitors the efficiency of the catalytic converter through the use of two oxygen sensors. When the converter cannot convert toxic gases the computer turns on the check engine light, usually with the code P0420 (catalytic efficiency below threshold). When the computer detects imminent damage to the converter, the check engine light will blink to inform the driver. In these cases, usually the diagnosis is quick and unequivocal. Several tests may be run to confirm that the catalyst no longer works well, and that the oxygen sensors policing the converter are functioning correctly. But this code usually indicates that converter replacement is necessary.

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What is the cost to repair a catalytic converter?

There’s no easy way to say it: replacing a catalytic converter is expensive. In some cases this repair will reach into the thousands of dollars, and the type of car you drive has a big impact on price.

Short Term Fix: $500-800

Non factory converters will work nearly as well as the original factory converter, and can bring the price of the job down into the $500–$800 range. Generally, they won’t have the same amount of precious metal as the original, so they are not as efficient; but they will keep the check engine light off. For foreign applications, the efficiency threshold is much tighter. Less expensive aftermarket converters are available, but the check engine light usually returns within a short interval.

Non factory converters will work nearly as well as the original factory converter, and can bring the price of the job down into the $500 to $800 range. Generally, they do not have the same amount of precious metal as the original, so they are not as efficient, but they will keep the check engine light off. For foreign applications, the efficiency threshold is much tighter. Less expensive aftermarket converters are available, but the check engine light returns within a short interval.

Long Term fix: $1200-1800

Openbay recommends using an OEM (factory) converter for a permanent repair. The price of the job, including parts and labor, will rise into the $1200–$1500 range, possibly higher on exclusive models. Again, pricing will vary by location and your vehicle make and model. Use Openbay to compare pricing for catalytic converter replacement from repair shops in your area.

Service article written by an ASE Master Technician

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