Catalytic Converter: Description and Operation

Catalytic Converters - XJS 4.0L:

Purpose and Operation
Catalytic converters are fitted into the exhaust system to reduce carbon monoxide and hydrocarbon emissions. Four ceramic monolith converters are mounted in the exhaust system, one pair in the down- pipe close to the engine and two in an under-body location.

In order for the catalytic converters to function correctly, it is necessary to control very closely the oxygen concentration in the exhaust gas entering the catalyst. This is achieved by the engine management system which continuously monitors the oxygen content of the exhaust gas by means of an oxygen sensor which is fitted to the rear of the down-pipe catalytic converter. This sensor adjusts the fuelling level to obtain the required oxygen content.

Unleaded fuel must be used on catalyst equipped vehicles and labels are displayed to indicate this. The filler cap is designed to accommodate unleaded fuel pump nozzles only.