Mileage Calibration Switch: Description and Operation

Mileage Sensor (No. 1 And No. 2):

Because of unique problems (such as oil injection) associated with controlling rotary engine emissions, Mazda incorporates a secondary air injection system with performance characteristics that vary with vehicle mileage. Two mileage sensors are located in the speedometer assembly. Sensor no. 1 is "OFF" below 20,000 miles (34,000 km) and "ON" above. Sensor no. 2 is only "ON" below 600 miles (1000 km). With these inputs, the ECU compensates for engine condition changes by altering the distribution of secondary air in a manner designed to both reduce emissions and extend the service life of components such as catalytic converters and oxygen sensors.