Oxygen Sensor: Description and Operation

Oxygen Sensor:

PURPOSE
By monitoring the oxygen sensor output voltage, the computer can determine the amount of oxygen in the exhaust gas and adjust the air/fuel mixture accordingly.

OPERATION
The sensor monitors atmospheric air versus exhaust gas oxygen content to produce a voltage output. This voltage ranges from approximately 0.1 volt (high oxygen - lean mixture) to 1.0 volt (low oxygen - rich mixture). A Code 13 sets in one minute if the voltage remains between 0.35 and 0.55 volts, but the system will go into "Open Loop" in approximately fifteen seconds. The Engine Control Module (ECM) counts each time the voltage crosses the 0.45 volt reference signal. These "cross counts" are indicated on a "Scan" tool.