- Carbon Monoxide (CO) → Carbon Dioxide (CO2)
- Hydrocarbons (HC) → Water (H2O)
- Oxides of Nitrogen (NOx) → Nitrogen (N2)
A three-way catalyst can cut CO, HC and NOx by over 99% if the air to fuel ratio is accurately controlled. Three-way catalysts will only give full conversion of each of these three pollutants in a gas stream containing a stoichiometric ratio of CO and NOx.