Dual Catalytic Converter

This converter assembly consists of two separate converters in one shell, with a mixing chamber in between. The forward converter is designed to control all three major emissions (NOx, HC, CO), and is therefore called a three-way catalyst (TWC). The rear converter is a conventional oxidation catalyst (COC) and controls only HC and CO.

As gases flow out of the TWC, they mix with air from the air pump system. This mixing is required to allow the rear converter to properly control HC and CO emissions.