🔧 BRZ - Oxygen Sensor Replacement

Your BRZ has two exhaust sensors: the front A/F (air-fuel) sensor before the catalytic converter, and the rear O2 sensor after the catalytic converter. Replacement is mostly the same idea for both: unplug the connector, remove the sensor with the correct socket, and install/torque the new one.

Difficulty Level: Intermediate | Estimated Time: 1-2 hours

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⚠️ Safety & Precautions

• 🛑 Let the exhaust fully cool (hot enough to burn skin).
• 🛑 Support the car with jack stands on solid, level ground—never rely on a jack alone.
• 🛑 Keep wires away from the exhaust when reinstalling (melt risk).
• 🛑 If you disconnect the battery, you may lose radio presets.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 2-ton minimum)
• Jack stands (rated 2-ton minimum)
• Wheel chocks
• Safety glasses
• Mechanic gloves
• 10mm socket
• 3/8" drive ratchet
• 3/8" drive extension set
• 1/2" drive breaker bar
• 22mm oxygen sensor socket (slotted) (specialty)
• Torque wrench (10–80 ft-lb range)
• Trim clip removal tool
• Flat-blade screwdriver
• Penetrating oil
• OBD2 scan tool (specialty)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Front A/F (air-fuel) sensor (upstream) - Qty: 1
• Rear oxygen sensor (downstream) - Qty: 1

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📋 Before You Begin

• Park on level ground, leave the transmission in 1st gear, and set the parking brake.
• Chock the rear wheels with wheel chocks.
• Spray penetrating oil at the sensor threads (where it screws into the exhaust) and let it soak 10–15 minutes.
• If you want to be extra safe around connectors, disconnect the negative battery terminal using a 10mm socket.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Raise and support the car

• Use a floor jack (rated 2-ton minimum) to lift the front of the car at the approved front jack point.
• Place jack stands (rated 2-ton minimum) under the front support points and lower the car onto them.
• Give the car a gentle shake to confirm it is stable before going underneath.

Step 2: Remove the front undertray (splash shield)

• Use a 10mm socket and 3/8" drive ratchet to remove the bolts.
• Use a trim clip removal tool (a fork-shaped pry tool) or flat-blade screwdriver to pop out any plastic clips.
• Set the undertray hardware aside so nothing gets lost.

Step 3A: Front sensor (A/F sensor) — locate and unplug

• Look for the sensor threaded into the exhaust before the catalytic converter, with a wire running to a connector.
• Release the connector lock and unplug it by hand. If needed, gently help the tab with a flat-blade screwdriver.
• Don’t pull on the wire—pull on the connector.

Step 3B: Rear sensor (downstream O2) — locate and unplug

• Look for the sensor threaded into the exhaust after the catalytic converter, with a wire running to a connector.
• Release the connector lock and unplug it by hand (assist the tab with a flat-blade screwdriver if needed).

Step 4: Remove the old sensor

• Spray a little more penetrating oil at the sensor threads if it looks rusty.
• Slip the wire through the side opening of the 22mm oxygen sensor socket (slotted) (specialty).
• Use a 3/8" drive ratchet with a 3/8" drive extension set to loosen it.
• If it’s very tight, switch to a 1/2" drive breaker bar (more leverage) with the 22mm oxygen sensor socket (slotted) (specialty).
• Once loose, spin it out by hand and remove it.

Step 5: Install the new sensor

• Thread the new sensor in by hand first (this prevents cross-threading).
• Tighten with the 22mm oxygen sensor socket (slotted) (specialty) and a torque wrench (10–80 ft-lb range).
• Torque to 44 Nm (32 ft-lbs).
• Route the wire the same way the original was routed so it stays away from the exhaust.

Step 6: Plug in the connector and secure the harness

• Push the connector together until it clicks (no tools needed).
• Confirm the wire is not stretched, pinched, or touching hot exhaust parts.

Step 7: Reinstall the undertray and lower the car

• Reinstall the undertray using the 10mm socket, 3/8" drive ratchet, and the trim clip removal tool as needed.
• Raise the car slightly with the floor jack (rated 2-ton minimum), remove the jack stands (rated 2-ton minimum), and lower the car.

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✅ After Repair

• Reconnect the battery (if disconnected) using a 10mm socket.
• Use an OBD2 scan tool (specialty) to clear any stored check-engine codes.
• Start the engine and listen for exhaust leaks (a sharp “ticking” near the sensor area can indicate a sealing/thread issue).
• Take a short test drive, then re-check that the sensor wire is still safely routed away from the exhaust.

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💰 DIY vs Shop Cost

Shop Cost: $250-$550 (parts + labor)

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

You Save: $170-$250 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1-2 hours.

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🎯 Ready to get started?

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