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

Warnings

Tools required

Parts

• Downstream oxygen sensor (Bank 1 Sensor 2) × 1 — Use OEM specification

Preparation

1. Ensure the exhaust system is completely cool before beginning work
2. Park vehicle on level ground and engage parking brake
3. Place wheel chocks behind rear wheels
4. Raise front of vehicle using jack and support securely on jack stands at designated lift points
5. Locate the downstream oxygen sensor on the exhaust pipe after the catalytic converter, accessible from underneath the vehicle

Procedure

1. 1

   Disconnect sensor electrical connector
   Locate the wiring harness connector for the downstream O2 sensor. Press the release tab and carefully disconnect the electrical connector. If the connector is corroded or stuck, gently wiggle while pulling to separate.
2. 2

   Free wiring harness clips
   Trace the sensor wiring and release any retaining clips or brackets securing the harness to the exhaust or chassis. This prevents damage to the wiring during sensor removal.
3. 3

   Apply penetrating oil if needed
   If the sensor appears corroded or the vehicle has high mileage, spray penetrating oil around the sensor threads and allow it to soak for 10-15 minutes. This helps prevent thread damage during removal.
   ⚠Keep penetrating oil away from the sensor tip to avoid contamination
4. 4

   Remove downstream oxygen sensor
   Using a 22mm oxygen sensor socket with ratchet and extension, turn the sensor counterclockwise to remove. The socket cutout allows clearance for the wiring. If resistance is encountered, do not force; reapply penetrating oil and wait longer.
5. 5

   Inspect and clean threads
   Once the old sensor is removed, inspect the exhaust bung threads for damage or excessive carbon buildup. Use a wire brush to clean the threads if necessary, ensuring they are free of debris.
6. 6

   Prepare new sensor
   Remove the new oxygen sensor from its packaging. Apply a thin coat of anti-seize compound to the sensor threads only, being extremely careful not to get any on the sensor tip or protective sleeve. Use anti-seize sparingly.
   ⚠️Contamination of the sensor element with anti-seize will cause premature sensor failure
7. 7

   Install new oxygen sensor
   Thread the new sensor into the exhaust bung by hand to prevent cross-threading. Once hand-tight, use the oxygen sensor socket and torque wrench to tighten to specification. Ensure the wiring will route properly without strain or contact with hot exhaust components.
   Torque spec

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

   Route and secure wiring harness
   Route the sensor wiring along the same path as the original, ensuring it does not contact the exhaust pipe or any moving components. Secure the harness with any clips or brackets that were removed earlier.
9. 9

   Reconnect electrical connector
   Plug the electrical connector back together, ensuring it clicks securely into place. Verify the connection is fully seated and the locking tab is engaged.

Reassembly

1. Lower the vehicle from jack stands
2. Remove wheel chocks

Verification

• Start the engine and verify no exhaust leaks are present at the sensor location
• Check that the check engine light does not illuminate or that any previous O2 sensor codes have cleared
• Use an OBD-II scanner to verify the new sensor is reporting data correctly and no pending codes are present
• Test drive the vehicle for at least 10 minutes to allow the ECU to complete readiness monitors

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