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Catalytic Converters Are Big-Ticket Items

Original equipment converters are supposed to last upward of 150,000 miles or more, but may fail sooner for a number of reasons.


The hot topic here is catalytic converters. The converter is the big ticket item in the exhaust system.  Every vehicle sold in the U.S. since 1975 has one or more converters in its exhaust systems, and every vehicle since 1996 is equipped with a special “OBD” certified converter that reduces pollution even more.


Original equipment converters are supposed to last upward of 150,000 miles or more, but may fail sooner for a number of reasons. Catalyst contamination is a biggie, and the reason for that is that the engine may be burning oil. Oil contains zinc and phosphorus wear additives (called ZDDP), which can foul the catalyst.

That’s why the level of ZDDP has been drastically reduced in newer motor oils. Converters also can be damaged by severe overheating, which is often the result of ignition misfiring or a leaky exhaust valve.
Most motorists don’t know their converter has reached the end of the road until their vehicle fails an emissions test. A Check Engine light with a P0420 or P0430 fault code (catalyst efficiency fault) is usually a sure indication the converter needs to be replaced.


New original equipment converters are covered by an 8-year/80,000-mile federal emissions warranty, or up to 15 years/150,000 miles on some California hybrid vehicles. Once a converter is out of warranty, it can be replaced with an aftermarket converter. The replacement must be the same type as the original, and OBD compliant if it is for a 1996 or newer vehicle. Aftermarket converters have a 2-year/24,000-mile warranty.

California also has its own special requirements and rules for catalytic converters. For vehicles registered within the state of California, a replacement converter must be CA-certified with an C.A.R.B number stamped on the converter shell.  For CA vehicles that are outside of California, a 49-state OBD II converter is an acceptable replacement.


For older high-mileage vehicles that may have problems meeting emissions, some aftermarket replacement converters are available with catalysts that contain a special blend of metals or an extra thick layer of metals so the converter can safely handle higher levels of pollutants. This can help keep the Check Engine light off so the vehicle will meet emissions for a longer period of time.

Related items a customer may need when replacing a converter include clamps and gaskets, possibly new pipe hangers, the adjoining pipes (head pipe and exhaust pipe), a new “downstream” oxygen sensor (which monitors the operation of the catalyst) and replacement heat shields if the original shields are rusted, damaged or missing.

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