Warm Up/Three Way Catalytic Converter (WU-TWC) and Under-floor Three Way Catalytic Converter (Under-floor TWC)

The WU-TWC/TWC converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in the exhaust gas to carbon dioxide (CO2), nitrogen (N2), and water vapor.

WU-TWC ('09 - 11 models) 

Fig 1: Identifying Warm Up Three Way Catalytic Converter ('09-11 Models)

Courtesy of AMERICAN HONDA MOTOR CO., INC.

WU-TWC ('12 model) 

Fig 2: Identifying Warm Up Three Way Catalytic Converter ('12 Model)

Courtesy of AMERICAN HONDA MOTOR CO., INC.

UNDER-FLOOR TWC 

Fig 3: Sectional View Of TWC (Under Floor)

Courtesy of AMERICAN HONDA MOTOR CO., INC.