exhaust

O2 Sensors - All

for 2021 Toyota RAV4 2.5L I4 · AWD

Difficulty

Moderate

Time

1.6 h

Tools

Steps

🤖AI-generated, not yet human-verified. This walkthrough was produced by AI and may contain errors. Treat it as a guide, cross-check every step and torque value against the manufacturer's service manual, and stop if anything looks unsafe. This is a moderate-risk job — take extra care.

This procedure covers removal and replacement of all oxygen sensors (upstream and downstream) on the 2019-2024 Toyota RAV4 2.5L I4 FWD engine.

Warnings

⚠️Exhaust system must be completely cool before starting work. Surface temperatures can exceed 500°F during normal operation.

⚠Oxygen sensors are fragile. Avoid dropping them or contaminating the sensor tip with oil, grease, or anti-seize compound.

⚠Sensor threads can seize in the exhaust manifold. Apply penetrating oil and allow soaking time if vehicle has high mileage.

ℹ️This vehicle uses an Air/Fuel Ratio sensor upstream (Sensor 1) and a traditional heated oxygen sensor downstream (Sensor 2).

Tools required

22mm oxygen sensor socketEssential

3/8" drive ratchet with extensionEssential

Torque wrench (20-50 Nm range)Essential

Wire brush

Penetrating oil

Jack and jack standsEssential

Wheel chocksEssential

Anti-seize compoundEssential

Parts

Air/Fuel Ratio Sensor (Bank 1 Sensor 1) × 1 — 89467-42020 or equivalent
Heated Oxygen Sensor (Bank 1 Sensor 2) × 1 — 89465-42100 or equivalent

Preparation

Ensure engine and exhaust system are completely cool to the touch
Disconnect negative battery terminal and wait 3 minutes for airbag system to discharge
Raise front of vehicle and support securely on jack stands at manufacturer jacking points
Place wheel chocks behind rear wheels
Remove engine undercover panels if equipped to access exhaust system
Locate both oxygen sensors: Sensor 1 (upstream) is mounted in exhaust manifold before catalytic converter, Sensor 2 (downstream) is after catalytic converter
Spray sensor threads with penetrating oil if vehicle has over 50,000 miles and allow 15-20 minutes soak time

Procedure

1
Disconnect upstream sensor electrical connector
Locate the Air/Fuel Ratio sensor (Sensor 1) wiring harness connector near the exhaust manifold heat shield. Press the locking tab and disconnect the connector. Follow the wire routing and release any clips securing the harness to the engine or exhaust.
2
Remove upstream Air/Fuel Ratio sensor
Using a 22mm oxygen sensor socket and ratchet with extension, carefully loosen the Air/Fuel Ratio sensor from the exhaust manifold. Turn counterclockwise to remove. The sensor socket cutout allows the wire to pass through. If sensor is difficult to turn, apply additional penetrating oil and wait, or carefully heat the manifold bung area with a torch (avoid heating the sensor itself).
3
Disconnect downstream sensor electrical connector
Locate the downstream Heated Oxygen Sensor (Sensor 2) connector underneath the vehicle, typically secured to the body or frame rail. Press the locking tab and disconnect. Release any harness clips along the routing path.
4
Remove downstream Heated Oxygen sensor
Using the 22mm oxygen sensor socket, loosen and remove the downstream sensor from the exhaust pipe after the catalytic converter. Turn counterclockwise to remove. Take care not to damage the exhaust pipe threads.
5
Inspect and clean sensor bungs
Inspect both sensor mounting locations for damaged threads or excessive carbon buildup. Use a wire brush to clean the threads in both bungs. Ensure no debris will enter the exhaust system. Check that thread chaser or tap is not necessary for damaged threads.
6
Prepare new upstream sensor
Remove new Air/Fuel Ratio sensor from packaging. Apply a thin coat of anti-seize compound to the threads only, being extremely careful to avoid getting any on the sensor tip or ceramic element. Contamination will cause sensor failure and catalytic converter damage.
7
Install upstream Air/Fuel Ratio sensor
Thread the new upstream sensor into the exhaust manifold by hand to avoid cross-threading. Once hand-tight, use the torque wrench and 22mm sensor socket to tighten to specification. Ensure the wire routing does not contact hot exhaust components or moving parts.
Torque spec
O2 Sensor45 Nm (33 lb-ft)
8
Prepare new downstream sensor
Remove new Heated Oxygen Sensor from packaging. Apply a thin coat of anti-seize compound to the threads only. Do not contaminate the sensor tip.
9
Install downstream Heated Oxygen sensor
Thread the new downstream sensor into the exhaust pipe after the catalytic converter by hand until snug. Use the torque wrench and 22mm sensor socket to tighten to specification. Route the wire away from heat sources and ensure it will not contact the driveshaft or suspension components during operation.
Torque spec
O2 Sensor45 Nm (33 lb-ft)
10
Connect sensor electrical connectors
Connect both oxygen sensor electrical connectors, ensuring they click fully into place. Secure all harness clips along the routing path. Verify no wires are pinched, stretched, or in contact with hot or moving components.
11
Reinstall undercovers and lower vehicle
Reinstall any engine undercover panels that were removed. Remove jack stands and carefully lower the vehicle to the ground. Reconnect the negative battery terminal.

Reassembly

Double-check that both sensor connectors are fully seated and locked
Verify all wiring is properly routed and secured away from heat and moving parts
Ensure all undercover panels are properly reinstalled and secured

Verification

Start the engine and verify it runs smoothly without check engine light illumination
Allow engine to reach operating temperature and confirm no exhaust leaks are present at either sensor location
Use an OBD-II scanner to verify oxygen sensor readings are present and responding normally
Perform a test drive and monitor for any check engine light or sensor-related diagnostic codes
Verify oxygen sensor heater circuit operation by checking live data: both sensors should show heater active and voltage switching after warmup