Replace the direct-fit catalytic converter on a 2018-2024 Toyota Camry 2.5L I4, including removal of oxygen sensors, exhaust components, and heat shields.

Warnings

Tools required

Parts

• Direct-fit catalytic converter assembly × 1 — OEM or 49-state EPA/CARB compliant aftermarket
• Exhaust flange gaskets × 2 — Use OEM specification
• Exhaust manifold gasket × 1 — Use OEM specification
• Oxygen sensor (upstream/front) × 1 — Reuse if in good condition
• Oxygen sensor (downstream/rear) × 1 — Reuse if in good condition
• Anti-seize compound × 1 — Nickel-based high temperature

Preparation

1. Ensure engine and exhaust system are completely cold (minimum 2 hours after operation)
2. Clear diagnostic trouble codes with OBD-II scanner and note any oxygen sensor or catalyst codes
3. Raise vehicle securely on jack stands at manufacturer lift points
4. Spray all exhaust fasteners with penetrating oil and allow to soak for 15-30 minutes
5. Disconnect negative battery terminal if equipped with active exhaust sensors

Procedure

1. 1

   Remove upstream oxygen sensor
   Locate the upstream (front) oxygen sensor on the exhaust manifold. Disconnect the electrical connector by pressing the release tab. Using the O2 sensor socket, turn counterclockwise to remove. If sensor is seized, apply heat carefully with a propane torch for 30 seconds.
2. 2

   Remove downstream oxygen sensor
   Locate the downstream (rear) oxygen sensor on the catalytic converter outlet pipe. Disconnect the electrical connector. Use the O2 sensor socket to remove by turning counterclockwise. Inspect sensor condition and replace if wire is damaged or sensor has over 100,000 miles.
3. 3

   Remove heat shields
   Remove the catalytic converter heat shield bolts from above and below the converter assembly. There are typically 4-6 bolts securing the shields. Carefully lower the heat shields to access the main converter.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
4. 4

   Disconnect exhaust at flange
   Locate the exhaust flange connection between the catalytic converter and the mid-pipe (approximately 18 inches behind the engine). Remove the two spring-loaded bolts or nuts securing the flange. Separate the connection and remove the old flange gasket.
   ⚠Spring-loaded bolts may release suddenly when loosened. Maintain control of fasteners.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
5. 5

   Remove converter from manifold
   From the engine bay, locate the exhaust manifold nuts securing the catalytic converter to the cylinder head. Remove the three manifold nuts (14mm) connecting the converter to the exhaust manifold. Support the converter weight from below while removing the final fastener.
   ⚠Catalytic converter assembly weighs approximately 15-20 lbs. Support from below before removing final fastener.
   Torque spec

   Manifold Nuts34 Nm (25 lb-ft)
6. 6

   Remove catalytic converter assembly
   Carefully maneuver the catalytic converter assembly down and out from the vehicle. You may need to angle it to clear the subframe and steering components. Disconnect any remaining hanger brackets as needed.
7. 7

   Clean mounting surfaces
   Using a wire brush, thoroughly clean the exhaust manifold mating surface and the flange connection point at the mid-pipe. Remove all old gasket material, carbon buildup, and corrosion. Inspect manifold studs for damage and replace if threads are stripped.
8. 8

   Install new oxygen sensors if replacing
   If installing new oxygen sensors, apply a thin coat of anti-seize compound to the threads only (avoid getting any on the sensor tip). Thread sensors by hand into the new catalytic converter until finger-tight, then torque to specification using the O2 sensor socket.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
9. 9

   Position new catalytic converter
   Place new exhaust manifold gasket onto the manifold studs. Carefully lift the new catalytic converter assembly into position, aligning the inlet flange with the exhaust manifold studs. Support the assembly weight while starting the manifold nuts by hand.
10. 10

    Secure converter to manifold
    Apply anti-seize compound to the manifold stud threads. Install all three manifold nuts and tighten in a cross pattern (alternating sides) to ensure even gasket compression. Torque to specification in two stages: first to 50% torque, then to final specification.
    Torque spec

    Manifold Nuts34 Nm (25 lb-ft)
11. 11

    Connect exhaust flange
    Install a new flange gasket between the catalytic converter outlet and the mid-pipe. Align the flange holes and install the flange bolts with springs. Apply anti-seize to bolt threads. Torque bolts evenly to specification.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
12. 12

    Reinstall heat shields
    Position heat shields around the catalytic converter assembly. Install and torque all heat shield bolts to specification. Ensure shields do not contact the converter surface and have proper clearance for expansion.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)
13. 13

    Connect oxygen sensor harnesses
    Route the oxygen sensor wiring through the factory clips and guides. Connect both upstream and downstream oxygen sensor electrical connectors, ensuring they click fully into place. Verify wiring has adequate clearance from hot exhaust components and moving suspension parts.

Reassembly

1. Verify all exhaust connections are tight and properly torqued
2. Ensure no tools or parts were left in the engine bay or under the vehicle
3. Reconnect negative battery terminal if disconnected
4. Double-check that all oxygen sensor connectors are fully seated

Verification

• Start engine and listen for exhaust leaks at manifold and flange connections
• Allow engine to reach operating temperature and check for any abnormal sounds or vibrations
• Use OBD-II scanner to verify oxygen sensor readings are normal (upstream fluctuating 0.1-0.9V, downstream stable around 0.45V)
• Perform a test drive and confirm no check engine light illuminates
• Inspect all connections from underneath after test drive for any signs of exhaust leaks or loose fasteners
• Monitor for catalyst efficiency codes (P0420) over the next 50-100 miles of driving

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