1/2 O2 Sensor Shorted to Ground (OBD II)
1/2 DOWNSTREAMName of Code:
O2S Voltage Shorted To Ground
When Monitored:
With engine coolant temperature above 170°F on the previous key on after a cold start. engine coolant below 98 ° F, and ambient battery sensor reading within 27°F of engine coolant.
Set Condition:
The oxygen sensor signal voltage is below 0.156 volts for 28 seconds after starting engine.
Theory of Operation:
The oxygen sensor is a voltage generating device. The PCM receives exhaust gas information from this O2 sensor. The sensor detects 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 sensor tells the PCM how welt its output signals are controlling the air/fuel ratio. Variations in the signal from this O2 sensor serve as air/fuel ratio indicators. Changes in the sensor signal occur because the air/fuel ratio is constantly changing. When oxygen content is low (rich mixture) the voltage signal will be low, approximately 0.1 volt.
Possible Causes:
- Sensor output wire shorted to ground
- Dirty/wet connection causing voltage tracking in connector
- O2 sensor failure
- Powertrain control module failure
- Connector terminals
- Connector wires