SW1 L4-1.9L SOHC VIN 8 (1996)
The oxygen sensor (O2S) consists of a zirconia electrolyte between two platinum plates. When the sensor reaches approximately 318°C (600°F) it
becomes an electrical source that responds to the oxygen content in the exhaust. The PCM produces a bias voltage of approximately 450 millivolts on the
oxygen sensor circuit. When the sensor is cold, its internal resistance is extremely high, therefore, the PCM recognizes the bias as an open circuit. As the
sensor warms up, the internal resistance decreases. When the sensor reaches approximately 318°C (600° F), it starts producing a voltage based on the
oxygen content in the exhaust stream. This voltage is used by the PCM to determine a rich or lean oxygen sensor signal and adjusts the fuel mixture
accordingly.
DIAGNOSTIC AIDS
