This procedure covers removal and installation of the front exhaust pipe (catalytic converter to manifold) on the 2018-2024 Toyota Camry 2.5L I4, including oxygen sensor handling and proper torque specifications.

Warnings

Tools required

Parts

• Front exhaust pipe with integrated catalytic converter × 1 — Use OEM specification
• Exhaust manifold to front pipe gasket × 1 — Use OEM specification
• Front pipe to catalytic converter gasket × 1 — Use OEM specification
• Exhaust flange nuts × 6 — 12mm nuts - replace if corroded
• Exhaust hanger rubber isolators × 2 — Replace if cracked or torn

Preparation

1. Park vehicle on level surface and allow exhaust system to cool completely (minimum 2 hours after last operation)
2. Raise front of vehicle and secure on jack stands at manufacturer-specified lift points
3. Spray all exhaust fasteners with penetrating oil and allow to soak for 15-30 minutes
4. Disconnect negative battery terminal (10mm socket) to prevent fault codes during oxygen sensor disconnection
5. Locate and identify both oxygen sensors: upstream sensor near manifold, downstream sensor near catalytic converter outlet

Procedure

1. 1

   Disconnect oxygen sensors
   Locate both oxygen sensor electrical connectors. Press the release tab and disconnect the upstream (Air-Fuel) sensor connector near the engine block. Disconnect the downstream (heated O2) sensor connector near the transmission tunnel. Ensure connectors are free from dirt and moisture.
2. 2

   Remove upstream oxygen sensor
   Using a 22mm oxygen sensor socket, carefully remove the upstream oxygen sensor from the exhaust manifold side of the front pipe. Turn counterclockwise. If sensor is seized, apply heat carefully with a propane torch to the bung area only, avoiding the sensor body and wiring. Inspect sensor threads and replace if damaged.
   ⚠Do not allow oxygen sensor to impact hard surfaces as this can damage the internal element and cause false readings.
   Torque spec

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

   Remove downstream oxygen sensor
   Using the 22mm oxygen sensor socket, remove the downstream oxygen sensor from the catalytic converter outlet section of the front pipe. Turn counterclockwise. Set sensor aside in a clean area where it will not be damaged.
   Torque spec

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

   Remove heat shield if equipped
   If heat shields are present around the front pipe, remove the mounting bolts using a 10mm socket. There may be shields on top and bottom of the pipe. Set shields aside for reinstallation.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
5. 5

   Disconnect front pipe from exhaust manifold
   Support the front pipe with one hand or a jack stand. Remove the three nuts (14mm) connecting the front pipe flange to the exhaust manifold. The pipe may drop slightly when the last nut is removed. Remove and discard the old gasket.
   ⚠Front pipe is heavy (approximately 20-25 lbs). Ensure adequate support before removing final fastener.
   Torque spec

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

   Disconnect front pipe from rear catalytic converter
   Locate the flange connection between the front pipe and the rear section of the exhaust system. Remove the two bolts (14mm) securing this connection. Support the rear section to prevent sagging. Separate the flanges and remove the old gasket.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
7. 7

   Remove exhaust hangers
   The front pipe is supported by rubber hanger isolators. Using a pry bar or screwdriver, carefully work the exhaust hanger loops out of the rubber isolators. There are typically two hangers supporting the front pipe assembly. Spray with soapy water to ease removal if necessary.
8. 8

   Remove front pipe from vehicle
   Carefully lower and maneuver the front pipe assembly out from under the vehicle. Watch for clearance around the transmission crossmember and steering components. Remove by angling the pipe toward the passenger side and then down.
9. 9

   Clean mating surfaces
   Use a wire brush to thoroughly clean the exhaust manifold flange surface and the rear exhaust flange surface. Remove all old gasket material, carbon deposits, and corrosion. Wipe surfaces clean with a shop rag. Inspect flanges for warping or damage.
   ℹ️Proper surface preparation is critical for leak-free connections. Take time to ensure surfaces are completely clean and flat.
10. 10

    Prepare new front pipe
    Inspect new front pipe for shipping damage. Apply a thin coat of anti-seize compound to the oxygen sensor threads (threads only, not the sensor tip). Apply anti-seize to the threads of all exhaust flange bolts and nuts that will be installed.
11. 11

    Install new front pipe assembly
    Maneuver the new front pipe into position, reversing the removal path. Align the pipe with the exhaust hangers first, then position the flanges. Insert hanger loops into rubber isolators. Support the pipe to maintain alignment with both flanges.
12. 12

    Connect front pipe to exhaust manifold
    Install the new manifold gasket onto the exhaust manifold studs with the correct orientation (usually marked TOP or with facing indicators). Position the front pipe flange against the gasket and start all three nuts by hand. Tighten nuts in a crisscross pattern to the specified torque.
    Torque spec

    Manifold Nuts34 Nm (25 lb-ft)
13. 13

    Connect front pipe to rear exhaust section
    Install the new flange gasket between the front pipe and rear section. Align the bolt holes and install both flange bolts by hand. Tighten bolts evenly to the specified torque.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
14. 14

    Install oxygen sensors
    Install the upstream oxygen sensor into the manifold-side bung on the front pipe. Apply anti-seize to threads only, avoiding the sensor tip. Hand-tighten first, then torque to specification. Repeat for the downstream sensor in the rear bung. Ensure sensor wiring is routed away from hot surfaces and moving components.
    ⚠Never apply anti-seize or lubricant to the oxygen sensor tip or element. This will contaminate the sensor and cause malfunction.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
15. 15

    Reinstall heat shields and connect sensors
    If heat shields were removed, reinstall them and torque bolts to specification. Reconnect both oxygen sensor electrical connectors, ensuring they click fully into place. Verify wire routing is secure and clear of exhaust components.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Reconnect negative battery terminal and torque to 10 Nm
2. Double-check all exhaust connections are tight and properly torqued
3. Verify all oxygen sensor connectors are fully seated and secured
4. Ensure exhaust hangers are properly seated in rubber isolators

Verification

• Lower vehicle and start engine. Listen for exhaust leaks at manifold and flange connections
• With engine at operating temperature, verify no hissing or ticking sounds from exhaust connections
• Check for exhaust odor in cabin which would indicate a leak near the firewall
• Use OBD-II scanner to verify no oxygen sensor fault codes are present (P0134, P0135, P0136, P0137, etc.)
• Perform a test drive and verify normal engine performance and no check engine light illumination
• After test drive, re-inspect all connections for signs of leakage (soot deposits) and verify torque if necessary

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