Catalytic converter (colloquially, “cat” or “catcon”)

A device used to reduce the toxicity of emissions from an internal combustion engine.

Working Principle of Three-way Catalytic converter:
Reduction of nitrogen oxides to nitrogen and oxygen: 2NO_x → xO₂ + N₂
Oxidation of carbon monoxide to carbon dioxide: 2CO + O₂ → 2CO₂
Oxidation of un-burnt hydrocarbons (HC) to carbon dioxide and water: C_xH_2x+2 + [(3x+1)/2]O₂ → xCO₂ + (x+1)H₂O

Catalytic Converter for Passat 1.8T 
Vehicle Model: Volkswagon Passat 1.8T / Audi A6 1.8T
Vehicle Year: 2000 ~ present
Engine: Inline 4 Cylinders 2.0L
Design: Single One
Converter Core: Ceramic Substrate 400cpsi (Honeycomb)
Outside Material: 409L Stainless Steel
Operating Way: Three-way
Emission Standard: Euro 2, 3, 4 / EPA Tier 1, 2, 3 / CARB