All 1975-81 Type 1 and 2 models sold in California and 1977-81 models sold in the other 49 states are equipped with catalytic converters. The converter is installed in the exhaust system, upstream and adjacent to the muffler.
Catalytic converters change noxious emissions of hydrocarbons (HC) and carbon monoxide (CO) into harmless carbon dioxide and water vapor. The reaction takes place inside the converter at great heat using platinum and palladium metals as the catalyst. If the engine is operated on lead-free fuel, they are designed to last 50,000 miles before replacement.
1979-81 Type 2 models sold in California are equipped with an oxygen sensor system installed in the exhaust pipe on the left side of the engine in back of the catalytic converter. At temperatures above 575ordm; F and for various compositions of gases, the sensor sends a signal to the AFC control unit which then corrects fuel injector operating time to insure accurately metered fuel/air mixture and keep the exhaust emissions within the legal limits. The sensor is coupled to a throttle valve switch which disconnects the sensor signal during full throttle. At all other times (except during engine warm up) the sensor is in operation.
The sensor must be replaced every 30,000 miles. A light on the speedometer lights at 30,000 mile intervals to alert you that sensor service is needed. After the service is done, reset the sensor light by pushing the button on the control box which is connected to the speedometer cable and is usually located behind the dash.