All 1975 and later (California) models, some 1979 (49 States) models and all 1980 and later (U.S. and Canada) models, are equipped with a catalytic converter, which is a muffler-shaped device installed in the exhaust system. The converter is filled with a monolithic substrate coated with small amounts of platinum and palladium. Through catalytic action, a chemical change converts carbon monoxide and hydrocarbons into carbon dioxide and water. The 1980 (California) models and all 1981 and later models, have a three-way catalytic converter. Platinum, palladium and rhodium are used in an oxidation/reduction process which acts on all three major constituents of exhaust pollution; HC and CO are oxidized in the usual manner into H 2 O and CO 2 , plus oxides of nitrogen are reduced to free oxygen and nitrogen (O 2 and N 2 respectively).
The 1975-78 (California) models have a floor temperature warning system, consisting of a temperature sensor installed onto the floor of the vehicle above the converter; a relay, located under the passenger seat and a light, installed on the instrument panel. The lamp illuminates when floor temperatures become abnormally high, due to converter or engine malfunction. The light also comes on when the ignition switch is turned to START , to check its operation. The 1979 and later models do not have the warning system.
The 1980 (California) models and all 1981 and later models have an oxygen sensor warning light on the dashboard, which illuminates at the first 30,000 mile (48,300 km) interval, signaling the need for oxygen sensor replacement. The oxygen sensor is part of the mixture ratio feedback system, described in this section. The feedback system uses the three-way converter as one of its major components.
No regular maintenance is required for the catalytic converter system, except for periodic replacement of the air induction system filter on 1980 (49 State) models. The air induction system is described earlier in this section. Filter replacement procedures are in General Information & Maintenance . The air induction system is used to supply the catalytic converter with fresh air; oxygen present in the air is used in the oxidation process.