Left or Right O2S Stays at Center
NAME OF CODELeft or Right O2S Stays at Center
WHEN MONITORED
After engine running for more than 2 minutes, then in closed loop mode and with the coolant temperature above 176°F.
SET CONDITION
The oxygen sensor (O2) signal voltage is greater than 4.8 volts.
THEORY OF OPERATION
The oxygen sensors are voltage generating devices. The Powertrain Control Module (PCM) receives exhaust gas information from the O2 sensors. The sensor(s) detect exhaust gas content by a galvanic reaction within the sensor that produces a voltage. After measuring the amount of oxygen in the exhaust gases, the oxygen sensors tell the PCM how well its output signals are controlling the air/fuel ratio. Variations in the signals from the O2 sensor(s) serve as air/fuel ratio indicators. Changes in the sensor signals occur because the air/fuel ratio is constantly changing. When oxygen content is low (rich mixture), the voltage signal will be high, approximately 1 volt. With a lean mixture (high oxygen content), the voltage signal will be low, approximately 0.1 volt.
POSSIBLE CAUSES
- O2 sensor failure
- Open O2 sensor signal circuit
- Open O2 sensor ground circuit
- Wiring harness/connectors