Circuit Description

The rear Heated Oxygen Sensors (HO2S) are used to determine oxygen storage capability of the converter. The rear HO2S diagnostics will run after the sensor has been active for more than 80 seconds and catalyst temperature is greater than 1112°F (600°C). DTC will set when signal being received by ECM is less than expected.

DTC will set when:

• Sensor signal voltage is less than 0.40 volt for more than 80 seconds.
• Rear oxygen sensor is in closed loop.
• No EVAP DTCs set.
• Catalytic converter temperature less than 1292°F (700°C).
• Battery voltage greater than 11.03 volts.