Catalytic Converter: Description and Operation

The catalytic converter system consists of a granular alumina carrier, coated with a catalyst (activated material) such as platinum or palladium and is enclosed in a heat resistant steel case.

When the mixture of the exhaust gases and secondary air is passed through the catalytic converter, the hydrocarbon (HC) and carbon monoxide (CO) content of the exhaust gases is oxidized and converted into water (H2O) and carbon dioxide (CO2).

The secondary air supplied by the Air Injection System is also used as the oxygen source for the oxidizing reaction.

Since large amounts of unburned fuel gases will cause the temperature of the catalytic converter to rise, a high temperature warning light is provided to warn of an overheating condition.

When secondary air from the Air Injection or Air Suction System is injected into the exhaust ports, the HC and CO in the exhaust gases will he oxidized. As the oxidation process continues, the temperature in the catalytic converter rises. When secondary air from the Air Injection System stops, the oxygen source required for the oxidation process is stopped and no further oxidation takes place. The temperature of the catalytic converter will drop, if the system is operating normally.