OBDII Automotive Articles - Catalytic Converter

Catalytic Converter

-Edited: Apr 07, 2022
-Popularity: 154 Views

Catalytic Converter

A Three-Way Catalytic (TWC) converter is used to reduce exhaust emissions. This type of converter can reduce hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx).

The upstream section of the converter contains a reducing/oxidizing bed to reduce NOx while oxidizing HC and CON. Αn air supply pipe from the air injection system injects air between the beds of the converter. Thus, the second converter bed oxidizes any remaining HC and CO to efficiently reduce exhaust emissions.

Although most original equipment (OEM) converters are designed to go over 100,000 miles, engine component problems could cause a premature failure. For example, phosphorus, which is found in motor oil, can foul the converter if the engine is burning oil due to leaking piston rings or worn-out valve guides or rings.

Unburned fuel is probably the most common cause of catalytic converters. A cylinder misfired, due to the faulty spark plug or ignition coil, and the leaking fuel injector could cause unburned fuel to enter the catalytic converter. The unburned fuel will cause the catalytic converter to overheat and damage the material inside.

Catalytic converter failures generally fall into the category of physical damage or catalyst failure. Physical damage usually can be visually identified – cracks, dents, etc. Internally, the structure can be cracked, broken, or melted. Where high heat may have led to catalyst failure, the engine and related systems need to be thoroughly checked.

Unfortunately, there is no way to repair the catalytic converter, and replacement is the only option. Up until the 1995 model year, converters were covered by a 5-year/50,000-mile federal emissions warranty (7 years or 70,000 miles in California). In 1995, the warranty was extended to 8 years or 80,000 miles.

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Catalytic Converter