This procedure covers the removal and replacement of the upstream (pre-catalytic converter) oxygen sensor on the 2018-2024 Toyota Camry 2.5L I4 engine.

Warnings

Tools required

Parts

• Upstream oxygen sensor (Air/Fuel sensor) × 1 — Use OEM specification

Preparation

1. Ensure the engine and exhaust system are completely cold
2. Park the vehicle on a level surface and apply parking brake
3. Place wheel chocks behind rear wheels
4. Raise the front of the vehicle with a floor jack and secure on jack stands at the proper lift points
5. Disconnect the negative battery terminal and wait 2 minutes before proceeding

Procedure

1. 1

   Locate the upstream oxygen sensor
   From underneath the vehicle, locate the upstream oxygen sensor on the exhaust manifold, before the catalytic converter. The sensor will have an electrical connector with a wire harness leading to it. On the 2.5L I4 engine, this sensor is positioned on the front exhaust pipe near the manifold flange.
2. 2

   Disconnect the electrical connector
   Trace the oxygen sensor wire to the electrical connector. Press the release tab and carefully disconnect the connector from the sensor. Gently wiggle the connector while pulling to avoid damaging the terminals. If the connector is stuck, do not force it - carefully work it free.
3. 3

   Prepare the sensor for removal
   If the sensor appears corroded or has been in place for an extended period, spray penetrating oil around the sensor threads where it enters the exhaust pipe. Allow the penetrating oil to soak for 5-10 minutes. Use a wire brush to clean debris from around the sensor base.
4. 4

   Remove the old oxygen sensor
   Using a 22mm oxygen sensor socket and ratchet with extension, turn the sensor counterclockwise to remove it. The sensor socket has a slot that allows the wire to pass through. Apply steady pressure - if the sensor is seized, do not force it excessively as this may damage the exhaust threads. Additional penetrating oil and time may be needed for stubborn sensors.
   ⚠If the sensor is extremely difficult to remove and the threads begin to strip, stop immediately and consult a professional to avoid damaging the exhaust manifold.
5. 5

   Inspect the exhaust threads
   Once the old sensor is removed, inspect the threads in the exhaust manifold for damage. Use a wire brush to clean the threads thoroughly, removing any carbon buildup or old anti-seize compound. Check that threads are clean and undamaged.
6. 6

   Prepare the new oxygen sensor
   Apply a small amount of anti-seize compound to the threads of the new oxygen sensor only. Apply sparingly and ensure none gets on the sensor tip or element. Spread the anti-seize evenly on the threads using your finger or a small brush. Keep the sensor element clean and protected.
   ⚠️Do not allow anti-seize or any contaminant to contact the sensor element. Contamination will cause immediate sensor failure and false readings.
7. 7

   Install the new oxygen sensor
   Thread the new oxygen sensor into the exhaust manifold by hand, ensuring the wire routing is correct and will not contact hot exhaust components. Turn the sensor clockwise by hand until it is finger-tight. Ensure the sensor threads in smoothly without cross-threading.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
8. 8

   Torque the oxygen sensor
   Using a torque wrench with the 22mm oxygen sensor socket, tighten the sensor to 45.0 Nm (33.0 lb-ft). Apply torque smoothly and verify the sensor is seated properly against the exhaust manifold.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
9. 9

   Connect the electrical connector
   Route the sensor wire harness to ensure it will not contact hot exhaust components or moving parts. Connect the electrical connector to the sensor, pressing firmly until you hear or feel a positive click indicating it is fully seated. Verify the connector is secure by gently tugging on it.
10. 10

    Lower the vehicle and reconnect battery
    Carefully lower the vehicle from the jack stands. Reconnect the negative battery terminal. The sensor replacement is now complete.

Reassembly

1. Ensure the oxygen sensor wire harness is properly routed and secured away from heat sources and moving components
2. Double-check that the electrical connector is fully seated and locked

Verification

• Start the engine and verify it runs normally without unusual idle or performance issues
• Check for exhaust leaks around the oxygen sensor - there should be no hissing or ticking sounds from the sensor location
• Using an OBD-II scanner, verify that no diagnostic trouble codes are present related to the oxygen sensor (P0130-P0167 range)
• Allow the engine to reach operating temperature and confirm the oxygen sensor data is being read by the ECU (values should fluctuate on a scan tool)
• Perform a short test drive and re-check for codes - the check engine light should remain off if installation was successful

More procedures for this vehicle