🔧 RX350 - Oxygen Sensor Replacement

Your RX350 can have multiple exhaust sensors, and the steps change depending on which one you’re replacing (upstream vs downstream, front bank vs rear bank). The job is mostly about safely accessing the sensor, unplugging it, and swapping it without damaging the wiring.

Difficulty Level: Intermediate | Estimated Time: 0.8-2.0 hours

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⚠️ Safety & Precautions

• ⚠️ Let the exhaust cool fully before touching sensors.
• ⚠️ Support the vehicle on jack stands; never rely on a jack.
• ⚠️ Keep the ignition OFF while unplugging sensor connectors.
• ⚠️ Do not twist/pull on the sensor wiring; only turn the hex.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Safety glasses
• Nitrile gloves
• 22mm oxygen sensor socket (specialty)
• 3/8" drive ratchet
• 3/8" drive torque wrench (10-100 Nm range)
• 3/8" drive extensions (3" and 6")
• Breaker bar (3/8" or 1/2")
• Trim clip removal tool
• Flathead screwdriver
• 10mm socket
• Penetrating oil
• OBD2 scan tool

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Upstream air/fuel ratio sensor (Sensor 1) - Qty: 1
• Downstream heated oxygen sensor (Sensor 2) - Qty: 1
• High-temperature anti-seize compound - Qty: 1

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📋 Before You Begin

• 🅿️ Park on level ground and set the parking brake.
• 🧱 Chock the rear wheels with wheel chocks.
• 🔍 Identify what you’re replacing:
  • Bank = which side of the V6; on a transverse V6, Bank 1 is typically the rear (firewall) side, and the other bank is toward the radiator.
  • Sensor 1 (upstream) = before the catalytic converter (in/near the exhaust manifold).
  • Sensor 2 (downstream) = after the catalytic converter (under the vehicle).
• 🧰 Use your OBD2 scan tool to read the code(s) and note which sensor it calls out (example: “Bank 1 Sensor 2”).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Confirm the exact sensor using a scan tool

• Plug in your OBD2 scan tool and read stored codes.
• Write down whether it says Bank 1 / Bank 2 and Sensor 1 / Sensor 2.
• This prevents replacing the wrong sensor.

Step 2: Raise and support the RX350 (for Sensor 2 / under-vehicle access)

• Place wheel chocks behind the rear wheels.
• Lift the front with a floor jack (rated 3-ton minimum).
• Set the front on jack stands (rated 3-ton minimum) at the proper lift points.

Step 3: Remove the lower cover (if it blocks access)

• Use a 10mm socket to remove bolts.
• Use a trim clip removal tool or flathead screwdriver to remove plastic clips.
• Set hardware aside in a tray so nothing gets lost.

Step 4: Locate the sensor and unplug the connector

• Find the sensor on the exhaust and follow its wire to the connector bracket.
• Release the connector lock by hand; if needed, use a flathead screwdriver gently.
• Move the harness out of the way so it can’t twist while you loosen the sensor.

Step 5: Loosen and remove the old oxygen sensor

• Spray the threads area with penetrating oil and wait 5–10 minutes.
• Slip on the 22mm oxygen sensor socket (specialty) over the wire and onto the sensor hex.
• Use a 3/8" drive ratchet with a 3/8" drive extension (3" or 6") to turn counterclockwise.
• If it’s very tight, use a breaker bar for extra leverage.
• Remove the sensor by hand once it breaks free.

Step 6: Install the new sensor (don’t cross-thread)

• Compare the new sensor to the old one (same connector and length).
• If the new sensor threads are not pre-coated, apply a tiny amount of high-temperature anti-seize compound to the threads only (keep it off the tip).
• Thread the new sensor in by hand first for several turns.
• Tighten using the 22mm oxygen sensor socket (specialty) and 3/8" drive torque wrench (10-100 Nm range).
• Torque to 44 Nm (32 ft-lbs).

Step 7: Reconnect wiring and reassemble

• Plug the connector back in until it clicks.
• Reclip the harness into its holders so it can’t touch the hot exhaust.
• Reinstall any covers using the 10mm socket and trim clip removal tool.

Step 8: Clear codes and verify the fix

• Lower the vehicle from the jack stands (rated 3-ton minimum) using the floor jack (rated 3-ton minimum).
• Use the OBD2 scan tool to clear codes.
• Start the engine and check for exhaust leaks or rattles near the sensor area.

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✅ After Repair

• 🧪 Do a 10–15 minute test drive with mixed city/highway if possible.
• 🧰 Recheck with the OBD2 scan tool for pending codes.
• 🔎 If a code returns immediately, double-check the connector is fully seated and the harness isn’t damaged.

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💰 DIY vs Shop Cost

Shop Cost: $250-$700 (parts + labor)

DIY Cost: $80-$300 (parts only)

You Save: $170-$400 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.8 hours.

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🎯 Ready to get started?

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