Air Fuel Ratio f A/F) Sensor

The A/F sensor operates over a wide air/fuel range. The A/F sensor is installed upstream of the warm up three way catalytic converter (WU-TWC), and sends signals to the ECM/PCM which varies the duration of fuel injection accordingly.

Fig 1: Cutway View Of Air Fuel Ratio (A/F) Sensor

Courtesy of AMERICAN HONDA MOTOR CO., INC.