Replace the downstream oxygen sensor (Bank 1 Sensor 2) located after the catalytic converter on the 2014-2019 Toyota Corolla 1.8L I4 engine.

Warnings

Tools required

Parts

• Downstream oxygen sensor (Bank 1 Sensor 2) × 1 — 89465-02110 or equivalent

Preparation

1. Ensure engine and exhaust system are completely cold
2. Raise vehicle and secure on jack stands at all four corners
3. Locate downstream oxygen sensor on exhaust pipe after catalytic converter, approximately below rear of engine compartment
4. If sensor is corroded, apply penetrating oil and allow 15-20 minutes soak time before removal

Procedure

1. 1

   Disconnect sensor electrical connector
   Locate the downstream O2 sensor wiring harness connector. Press the release tab and carefully disconnect the electrical connector. If connector is difficult to separate, gently wiggle while pulling to avoid breaking the locking tab.
2. 2

   Free wiring from retaining clips
   Trace the sensor wire back to any retaining clips or brackets securing it to the exhaust pipe or chassis. Release the wire from these clips to provide sufficient slack for sensor removal.
3. 3

   Remove old oxygen sensor
   Using a 22mm oxygen sensor socket and ratchet with extension, turn the sensor counterclockwise to remove. The sensor socket has a slot to accommodate the wiring. If sensor is seized, apply additional penetrating oil and allow to soak, or use careful heat application with a propane torch on the exhaust bung only (not the sensor itself).
4. 4

   Clean sensor bung threads
   With the old sensor removed, use a wire brush to clean the threads in the exhaust pipe bung. Remove any carbon buildup, corrosion, or old anti-seize compound to ensure proper seating and torque of the new sensor.
5. 5

   Prepare new oxygen sensor
   Apply a thin coat of anti-seize compound to the threads of the new oxygen sensor only. Do not allow anti-seize to contact the sensor tip or get inside the threaded bung. Use high-temperature nickel-based anti-seize rated for exhaust applications.
6. 6

   Install new oxygen sensor
   Thread the new sensor into the exhaust pipe bung by hand to avoid cross-threading. Once finger-tight, use the oxygen sensor socket and torque wrench to tighten to specification. Ensure the wiring exits in a position that routes naturally without sharp bends.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
7. 7

   Route and secure sensor wiring
   Route the sensor wire along the original path, ensuring it does not contact hot exhaust components or moving parts. Secure the wire in the original retaining clips and brackets. Verify sufficient slack exists to prevent tension on the connector.
8. 8

   Reconnect electrical connector
   Connect the oxygen sensor electrical connector to the vehicle harness. Push together firmly until the locking tab clicks into place. Gently tug to verify secure connection.

Reassembly

1. Lower vehicle from jack stands
2. Double-check that all electrical connections are secure and wiring is properly routed away from heat and moving parts

Verification

• Start the engine and verify no exhaust leaks are present at the oxygen sensor location
• Use an OBD-II scanner to clear any stored diagnostic trouble codes related to the downstream oxygen sensor
• Allow engine to reach operating temperature and verify the new sensor is providing readings (typically 0.1-0.9V fluctuating)
• Perform a test drive and confirm no check engine light illumination and no oxygen sensor-related codes return
• Re-check sensor torque after first heat cycle if possible to ensure it has not loosened

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