Catalytic Converter - California

Replace the California-compliant catalytic converter assembly on a 2015 Kia Forte 1.8L I4, including oxygen sensor transfer and exhaust system reconnection.

Warnings

Tools required

Parts

• California CARB-compliant catalytic converter assembly × 1 — Use OEM specification or CARB-certified aftermarket
• Exhaust flange gasket (upstream) × 1 — Use OEM specification
• Exhaust flange gasket (downstream) × 1 — Use OEM specification
• Exhaust flange nuts × 6 — M10 self-locking nuts

Preparation

1. Verify engine and exhaust system are completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Place wheel chocks behind rear wheels
4. Spray all exhaust flange bolts and oxygen sensor threads with penetrating oil
5. Raise front of vehicle and support securely on jack stands at factory lift points
6. Verify CARB certification number on replacement catalytic converter matches vehicle application

Procedure

1. 1

   Remove heat shield
   Locate the catalytic converter heat shield. Remove the heat shield mounting bolts using a 10mm socket. Carefully remove the heat shield and set aside for reinstallation.
   Torque spec

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

   Disconnect upstream oxygen sensor
   Locate the upstream (pre-cat) oxygen sensor electrical connector near the engine. Disconnect the connector by pressing the release tab. Using a 22mm oxygen sensor socket, carefully unthread the oxygen sensor from the exhaust manifold or front pipe. Avoid damaging the sensor if it will be reused.
   ⚠Oxygen sensor threads are fragile. Use proper oxygen sensor socket with wire access slot to prevent damage.
   Torque spec

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

   Disconnect downstream oxygen sensor
   Locate the downstream (post-cat) oxygen sensor on the catalytic converter assembly. Disconnect the electrical connector. Using the 22mm oxygen sensor socket, remove the downstream oxygen sensor from the catalytic converter. Inspect sensor condition.
   Torque spec

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

   Support catalytic converter
   Position a floor jack or support stand under the catalytic converter assembly to support its weight during removal. Ensure adequate support to prevent the component from falling when disconnected.
5. 5

   Disconnect exhaust hanger
   Locate the rubber exhaust hanger supporting the catalytic converter or connecting pipe. Remove the hanger bolt using appropriate socket or carefully separate the hanger from its mount. This provides clearance for catalytic converter removal.
   Torque spec

   Hanger Bolts19 Nm (14 lb-ft)
6. 6

   Remove upstream flange connection
   Locate the upstream flange connection between the exhaust manifold and catalytic converter. Remove the flange bolts using a 14mm socket. Carefully separate the flange connection and remove the old gasket. Inspect flange surfaces for damage or warping.
   ⚠Flange bolts may be seized. Do not use excessive force that could damage studs or flange. Apply heat carefully if necessary.
   Torque spec

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

   Remove downstream flange connection
   Locate the downstream flange connection between the catalytic converter and intermediate pipe. Remove the flange bolts using a 14mm socket. Carefully lower and remove the catalytic converter assembly from the vehicle. Remove and discard the old downstream gasket.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
8. 8

   Prepare mating surfaces
   Clean both upstream and downstream flange mating surfaces thoroughly using a wire brush. Remove all old gasket material, rust, and debris. Ensure surfaces are flat and free of damage. Clean oxygen sensor bungs in the new catalytic converter if sensors are being transferred.
   ℹ️Proper sealing requires clean, flat mating surfaces. Take time to properly prepare all connection points.
9. 9

   Install oxygen sensors in new catalytic converter
   Apply a thin coat of anti-seize compound to the oxygen sensor threads only, avoiding the sensor tip. Thread both upstream and downstream oxygen sensors into the new California-compliant catalytic converter by hand, then tighten to specification using the 22mm oxygen sensor socket and torque wrench.
   ⚠Never apply anti-seize to oxygen sensor tip or connector. Only apply to threads to prevent seizing in exhaust bung.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
10. 10

    Position new catalytic converter
    Position the new catalytic converter assembly into place using the support jack. Install new exhaust gaskets at both upstream and downstream flange connections. Align the flanges carefully to ensure proper gasket seating.
    ℹ️Ensure oxygen sensor wiring is routed clear of heat sources and moving components before securing flanges.
11. 11

    Install upstream flange connection
    Apply anti-seize compound to the threads of new or cleaned upstream flange bolts. Install and hand-thread all flange bolts. Tighten bolts in a cross-pattern to specification using a torque wrench to ensure even gasket compression.
    Torque spec

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

    Install downstream flange connection
    Apply anti-seize compound to the threads of new or cleaned downstream flange bolts. Install and hand-thread all flange bolts. Tighten bolts in a cross-pattern to specification using a torque wrench.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
13. 13

    Reconnect exhaust hanger and heat shield
    Reinstall the exhaust hanger and tighten to specification. Position the heat shield over the catalytic converter and install all heat shield bolts, tightening to specification. Ensure heat shield does not contact any part of the catalytic converter body.
    Torque spec

    Hanger Bolts19 Nm (14 lb-ft)

    Heat Shield Bolts10 Nm (7 lb-ft)
14. 14

    Connect oxygen sensor electrical connectors
    Route oxygen sensor wiring away from heat sources and moving parts. Connect both upstream and downstream oxygen sensor electrical connectors, ensuring they click securely into place. Verify proper connection by gently pulling on each connector.

Reassembly

1. Remove support jack from under catalytic converter
2. Visually inspect all connections to ensure proper assembly
3. Lower vehicle from jack stands
4. Remove wheel chocks

Verification

• Start engine and allow to idle. Listen for exhaust leaks at both flange connections and oxygen sensor bungs
• Visually inspect all connections while engine is running for signs of exhaust gas leakage
• Allow engine to reach operating temperature and verify no leaks develop under heat expansion
• Check that check engine light does not illuminate and oxygen sensor data is being received by ECU (use scan tool if available)
• Verify heat shield is properly secured and not vibrating or contacting catalytic converter
• Test drive vehicle and verify proper operation with no exhaust odors in cabin or unusual sounds
• Confirm CARB compliance documentation is retained with vehicle records as required by California law

More procedures for this vehicle