Oxygen Sensor: Description and Operation
COMPONENTHeated Oxygen Sensor (HO2S)
FUNCTION
Detects oxygen in exhaust mixture and outputs a variable voltage to PCM. PCM uses inputs from upstream HO2S to fine tune air/fuel ratio by controlling required fuel injector pulse width. Downstream sensors are monitors for normal switches.
REMARKS
HO2S produces a variable voltage at a HO2S top temperature of 350°C (662°F) as follows:
- High concentration of oxygen: less than 0.4 volt
- Low concentration of oxygen: greater than 0.6 volt
No interchangeability between upstream HO2S (green connector) and downstream HO2S (blue connector). HO2S identification is as follows:
- Upstream HO2S on # 1 cylinder bank: HO2S-1,1
- Upstream HO2S on opposite bank: HO2S-2,1
- Downstream HO2S: HO2S-1,2