Catalytic Converter - California

Remove and replace the California-specification catalytic converter assembly on a 2018-2024 Toyota Camry with 2.5L I4 engine, including oxygen sensor transfer and exhaust system reconnection.

Warnings

Tools required

Parts

• California-spec catalytic converter assembly × 1 — Use OEM or CARB-certified aftermarket
• Exhaust flange gasket × 1 — Use OEM specification
• Manifold gasket × 1 — Use OEM specification
• Oxygen sensor (if reusing existing) — Inspect before reuse

Preparation

1. Ensure engine and exhaust system are completely cold (minimum 2 hours after last operation)
2. Park vehicle on level surface and engage parking brake
3. Spray all exhaust fasteners with penetrating oil and allow to soak for 15-30 minutes
4. Raise vehicle securely on jack stands at manufacturer lift points
5. Verify adequate working clearance beneath vehicle (minimum 24 inches recommended)

Procedure

1. 1

   Remove heat shield
   Locate the catalytic converter heat shield. Remove the heat shield mounting bolts using a 10mm socket. There are typically 3-4 bolts securing the shield. Set heat shield aside for reinstallation.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
2. 2

   Disconnect upstream oxygen sensor
   Locate the upstream oxygen sensor (Bank 1 Sensor 1) on the catalytic converter near the exhaust manifold. Disconnect the electrical connector by pressing the tab and pulling straight out. Using a 22mm oxygen sensor socket, carefully turn counterclockwise to remove the sensor. If sensor is seized, apply heat carefully with a heat gun and retry. Inspect sensor condition and threads.
   ⚠Oxygen sensors are fragile. Do not use excessive force or allow socket to contact sensor tip. Contamination of sensor element will cause malfunction.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
3. 3

   Disconnect downstream oxygen sensor (if applicable)
   Locate the downstream oxygen sensor (Bank 1 Sensor 2) on the catalytic converter body near the outlet flange. Disconnect electrical connector and remove sensor using 22mm oxygen sensor socket, turning counterclockwise. Inspect sensor condition.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
4. 4

   Remove upper manifold flange connection
   Locate the three-bolt flange connection between the exhaust manifold and catalytic converter inlet. Support the catalytic converter weight with one hand or a transmission jack. Using a 14mm socket, remove the three manifold flange nuts. The flange may be difficult to separate due to corrosion. Use a flat pry bar if needed to gently separate the connection. Remove and discard the old gasket.
   ⚠Support catalytic converter weight before removing final fasteners to prevent sudden drop and potential injury or damage to brake lines.
   Torque spec

   Manifold Nuts34 Nm (25 lb-ft)
5. 5

   Disconnect mid-pipe flange connection
   Locate the two-bolt flange connection between the catalytic converter outlet and the mid-pipe. Using a 14mm socket, remove the two exhaust flange bolts. Apply penetrating oil if bolts resist turning. Separate the flange connection and remove the old gasket.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
6. 6

   Release exhaust hangers
   Locate the rubber exhaust hanger supporting the catalytic converter assembly. Using an exhaust hanger tool or pry bar, carefully unhook the metal loop from the rubber isolator. Work the hanger free without tearing the rubber bushing. Lower the catalytic converter assembly carefully and remove from vehicle.
7. 7

   Clean flange surfaces and inspect components
   Using a wire brush, thoroughly clean both the exhaust manifold outlet flange and the mid-pipe inlet flange. Remove all old gasket material, carbon buildup, and corrosion until metal surfaces are clean and flat. Inspect flange faces for warping, cracks, or damage. Verify oxygen sensor threads are clean and undamaged. Check exhaust hangers for tears or deterioration.
8. 8

   Install oxygen sensors in new catalytic converter
   Apply a small amount of anti-seize compound to the oxygen sensor threads only, being extremely careful not to contaminate the sensor tip. Thread the upstream oxygen sensor (Bank 1 Sensor 1) into the new catalytic converter by hand until finger-tight. Using the 22mm oxygen sensor socket and torque wrench, tighten to specification. Repeat for downstream sensor (Bank 1 Sensor 2).
   ⚠Apply anti-seize to threads only. Any contamination of the oxygen sensor element will cause sensor failure and check engine light.
   Torque spec

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

   Position new catalytic converter
   Position the new California-spec catalytic converter assembly under the vehicle. Engage the rubber exhaust hanger first to support the assembly weight. Align the inlet flange with the exhaust manifold and the outlet flange with the mid-pipe. Verify proper positioning before installing fasteners.
10. 10

    Install new manifold gasket and secure connection
    Place the new manifold gasket between the exhaust manifold and catalytic converter inlet flange. Ensure gasket is properly seated with all holes aligned. Apply anti-seize compound to the threads of the three manifold flange nuts. Install nuts finger-tight, then tighten in a star pattern using torque wrench to specification.
    Torque spec

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

    Install new flange gasket and secure mid-pipe connection
    Place the new flange gasket between the catalytic converter outlet and mid-pipe inlet. Verify alignment of all bolt holes. Apply anti-seize compound to the threads of the two exhaust flange bolts. Install bolts finger-tight, then torque to specification in a crisscross pattern.
    Torque spec

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

    Verify exhaust hanger engagement
    Inspect the rubber exhaust hanger to confirm the metal loop is fully seated in the isolator. The catalytic converter should hang freely without binding or stress on any connection points. Check clearance between exhaust components and surrounding parts (frame, driveshaft, fuel lines, brake lines). Minimum 1 inch clearance required at all points.
13. 13

    Reconnect oxygen sensor electrical connectors
    Route oxygen sensor wiring along factory path, ensuring no contact with hot exhaust components. Connect the electrical connectors for both upstream and downstream oxygen sensors, pressing firmly until an audible click confirms engagement. Verify connector locks are engaged and wiring has adequate slack for thermal expansion.
14. 14

    Reinstall heat shield
    Position the heat shield over the catalytic converter, aligning all mounting holes. Install heat shield bolts and torque to specification. Ensure heat shield does not contact the catalytic converter body and has proper clearance (at least 10mm gap).
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Double-check all exhaust connections are properly torqued and gaskets are seated
2. Verify all oxygen sensor electrical connections are secure and wiring is routed away from heat sources
3. Confirm exhaust system has proper clearance from all surrounding components with no contact points
4. Lower vehicle from jack stands carefully

Verification

• Start engine and listen for exhaust leaks at all flange connections. Any hissing or ticking noise indicates improper seating or loose fasteners
• With engine running, visually inspect all connections for smoke or exhaust gas escaping from joints
• Rev engine to 2500 RPM while in Park and verify no abnormal vibrations or rattles from exhaust system
• Check for check engine light or trouble codes related to oxygen sensors. Clear any codes that may have been set during installation and verify they do not return
• Allow engine to reach operating temperature and verify oxygen sensor readings are within normal range using OBD-II scanner
• Perform visual inspection after first 50-100 miles of driving to check for any exhaust leaks, loose fasteners, or thermal damage

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