Location: In the exhaust manifold or header, before the catalytic converter

Function:

• Monitors the oxygen level in exhaust gases before they reach the catalytic converter

• Sends data to the ECM to adjust the air-fuel ratio for optimal performance, efficiency, and emissions

Install Tips:

1. Cool Engine First: Exhaust components get extremely hot—wait until everything cools down.

2. Disconnect Battery: Prevents accidental shorts while unplugging the sensor.

3. Locate Sensor: It's mounted upstream (before the catalytic converter), usually on or near the exhaust manifold.

4. Unplug Connector: Carefully disconnect the wiring harness—press the tab and pull from the connector, not the wires.

5. Remove Old Sensor:

   • Use an O2 sensor socket or 22mm wrench

   • Spray penetrating oil if it’s stuck, let it soak

6. Prep New Sensor:

   • Most come with anti-seize pre-applied—if not, use a small amount (keep off sensor tip)

7. Install New Sensor:

   • Thread in by hand to avoid cross-threading

   • Tighten snugly (30–40 ft-lbs if torque spec is needed)

8. Reconnect Harness: Ensure a firm click and route the wire away from heat or moving parts.

9. Clear Codes: If you had a CEL, clear it with a scan tool or wait for it to reset after some driving.

See diagrams for each engine model of placement.