Catalytic Converter - California

Replace the catalytic converter assembly on a 2015-2020 Ford F-150 with 3.5L EcoBoost V6 engine to meet California emissions standards.

Warnings

Tools required

Parts

• Catalytic converter assembly (California CARB-compliant) × 1 — Use OEM specification
• Exhaust flange gaskets × 2 — Use OEM specification
• Oxygen sensor(s) × 2 — Reuse if in good condition or replace

Preparation

1. Ensure engine and exhaust system are completely cold
2. Park vehicle on level ground and engage parking brake
3. Raise front of vehicle and support securely on jack stands at frame contact points
4. Spray all exhaust flange bolts, oxygen sensor threads, and heat shield bolts with penetrating oil and allow to soak for 15-30 minutes
5. Disconnect negative battery cable to prevent O2 sensor fault codes during replacement

Procedure

1. 1

   Remove heat shields
   Locate and remove heat shield bolts securing the exhaust heat shields around the catalytic converter area. Remove shields carefully to access the catalytic converter and oxygen sensors. Note the position of all heat shields for proper reinstallation.
   Torque spec

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

   Disconnect oxygen sensors
   Locate the upstream and downstream oxygen sensors on the catalytic converter assembly. Disconnect the electrical connectors by pressing the release tabs. Using an O2 sensor socket, carefully remove both oxygen sensors from the catalytic converter. If reusing sensors, handle carefully to avoid damaging the sensor tips.
   ⚠O2 sensor threads are easily damaged. Use proper O2 sensor socket and turn slowly to prevent cross-threading.
   Torque spec

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

   Disconnect upstream exhaust flange
   Locate the flange connection between the exhaust manifold and catalytic converter inlet. Support the catalytic converter with one hand or a suitable support. Remove the flange bolts connecting the turbocharger/exhaust manifold outlet to the catalytic converter inlet. Separate the flange and remove the old gasket.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
4. 4

   Disconnect downstream exhaust flange
   Locate the flange connection between the catalytic converter outlet and the mid-pipe. Remove the flange bolts securing this connection. Separate the flange carefully and remove the old gasket. Keep track of any spacers or alignment hardware.
   Torque spec

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

   Remove exhaust hangers
   Locate the rubber exhaust hangers supporting the catalytic converter assembly. Using an exhaust hanger removal tool or pry bar, carefully disconnect the exhaust hangers from their mounting points. Work from rear to front to allow the exhaust to pivot downward.
   ⚠Exhaust hangers are under tension. Control the exhaust system as hangers are released to prevent sudden dropping.
   Torque spec

   Hanger Bolts23 Nm (17 lb-ft)
6. 6

   Remove catalytic converter
   With all connections and hangers disconnected, carefully lower and remove the catalytic converter assembly from the vehicle. The assembly may be heavy and awkward to maneuver. Work carefully to avoid damaging brake lines, fuel lines, or other components.
   ℹ️Catalytic converter assemblies contain precious metals. Old converters have core value and should be returned for recycling.
7. 7

   Clean mating surfaces
   Using a wire brush, thoroughly clean all exhaust flange mating surfaces at both the upstream and downstream connections. Remove all carbon deposits, old gasket material, and corrosion to ensure proper sealing. Inspect flange surfaces for warping or damage.
   ⚠Ensure all debris is removed from the exhaust system to prevent blockages and proper gasket sealing.
8. 8

   Prepare new catalytic converter
   Unpack the new California-compliant catalytic converter and verify it matches the original configuration. Check that all oxygen sensor ports are present and accessible. Apply anti-seize compound to oxygen sensor threads only, avoiding the sensor tips.
   ⚠Do not get anti-seize compound on oxygen sensor tips as this will contaminate and ruin the sensors.
9. 9

   Install oxygen sensors
   Thread the oxygen sensors into the new catalytic converter by hand to ensure proper engagement. Once hand-tight, use the O2 sensor socket and torque wrench to tighten to specification. Ensure electrical connectors are accessible and positioned to avoid heat damage.
   Torque spec

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

    Position new catalytic converter
    Carefully lift and position the new catalytic converter assembly into place. Align the inlet and outlet flanges with their mating connections. Thread hanger bolts or install rubber hangers loosely to support the assembly but allow movement for final alignment.
    Torque spec

    Hanger Bolts23 Nm (17 lb-ft)
11. 11

    Install upstream flange connection
    Install a new exhaust flange gasket at the upstream connection between the exhaust manifold/turbocharger and catalytic converter inlet. Apply anti-seize to the exhaust flange bolt threads. Install bolts and tighten in a crisscross pattern to specification to ensure even gasket compression.
    Torque spec

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

    Install downstream flange connection
    Install a new exhaust flange gasket at the downstream connection between the catalytic converter outlet and mid-pipe. Apply anti-seize to flange bolt threads. Install bolts and tighten in a crisscross pattern to specification.
    Torque spec

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

    Secure exhaust hangers
    With both flanges secured, verify the catalytic converter is properly aligned and not binding or stressed. Ensure all rubber exhaust hangers are fully seated in their mounting points. Tighten any hanger bolts to specification.
    Torque spec

    Hanger Bolts23 Nm (17 lb-ft)
14. 14

    Reinstall heat shields
    Reinstall all heat shields in their original positions. Ensure shields do not contact the catalytic converter directly and maintain proper clearance. Install and tighten heat shield bolts to specification.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)
15. 15

    Connect oxygen sensors and battery
    Connect the electrical connectors to both oxygen sensors, ensuring the connectors click securely into place and are routed away from heat sources. Reconnect the negative battery cable. Clear the work area and ensure no tools or parts remain under the vehicle.

Reassembly

1. Verify all exhaust connections are secure and properly torqued
2. Ensure all heat shields are reinstalled and properly positioned
3. Check that oxygen sensor wiring is routed away from hot exhaust components
4. Confirm all exhaust hangers are properly seated and supporting the system

Verification

• Lower vehicle and start engine, listening for any exhaust leaks at flange connections
• Allow engine to reach operating temperature and verify no abnormal sounds or vibrations from exhaust system
• Check for exhaust leaks by feeling around flange connections for escaping gases (use caution around hot components)
• Use a scan tool to verify oxygen sensors are reading properly and no diagnostic trouble codes are present
• Verify check engine light is not illuminated and readiness monitors begin to set after test drive
• Perform a final visual inspection under the vehicle for proper clearance and alignment of all exhaust components

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