Catalyst Monitoring

Precise control of the fuel and air mixture to the specified stoichiometric level is essential to the proper function of the three way catalyst. The catalyst oxidizes Carbon Monoxide (CO) and Hydrocarbons (HC), while reducing Nitrous Oxide (NOx).

Deterioration of catalyst efficiency leads to a higher level of emissions. In order to be able to detect a change in the efficiency of the catalyst, the control system must observe both the incoming and the outgoing exhaust gases. To achieve this aim, exhaust gas oxygen sensors are fitted both upstream and downstream of the catalytic converter.