The Heated Oxygen Sensor (HO2S) detects the presence of oxygen in the exhaust and produces a variable voltage according to the amount of oxygen detected. A high concentration of oxygen (lean air/fuel ratio) in the exhaust produces a low voltage signal less than 0.4 volt. A low concentration of oxygen (rich air/fuel ratio) produces a high voltage signal greater than 0.6 volt. The HO2S provides feedback to the PCM indicating air/fuel ratio in order to achieve a near stoichiometric air/fuel ratio of 14.7:1 during closed loop engine operation.
Removal & Installation
- Disconnect the negative battery cable.
- Remove the engine appearance cover, 4.2L Engines only.
- Raise and safely support the vehicle, except 4.2L Engines.
- Disconnect the Heated Oxygen Sensor (HO2S) electrical connector.
- Using a suitable oxygen sensor socket, remove the HO2S.
- Installation is the reverse order of removal. Tighten the HO2S to 34 ft. lbs. (46 Nm).
Inspect the air cleaner and inlet duct. Check all engine vacuum hoses for damage, leaks, cracks, kinks and proper routing. Check Electronic Control (EC) system wiring harness for proper connections, bent or broken pins, corrosion, loose wires and proper routing. Check the powertrain control module (PCM), sensors, and actuators for physical damage.
Basic circuit checks help to minimize pinpoint test steps by providing a procedure to diagnose harness faults associated with the Electronic Engine Control (EC) System: