Oxygen Sensor: Description and Operation

Heated Oxygen Sensor:

PURPOSE
The Heated Gas Oxygen Sensor (HO2S) detects the presence of oxygen in the exhaust stream producing a variable voltage according to the amount of oxygen detected.

OPERATION
A high concentration of oxygen (lean condition) in the exhaust produces a low voltage below 0.4 volts. A low concentration of oxygen (rich condition) in the exhaust produces a high voltage greater than 0.6 volts. The Powertrain Control Module (PCM) reads this signal to achieve an air/fuel ratio of 14.7:1 when operating in "CLOSED LOOP."
For more effective operating conditions the HO2S is heated to improve cold weather driveablity.