Catalytic Converter - Direct Fit

This procedure covers the removal and replacement of the direct-fit catalytic converter on the 2015-2020 Ford F-150 with the 3.5L EcoBoost V6 engine, including oxygen sensor removal and exhaust system disconnection.

Warnings

Tools required

Parts

• Direct-fit catalytic converter assembly × 1 — OEM or 49-state/CARB compliant aftermarket
• Exhaust flange gaskets × 2 — Use OEM specification
• Oxygen sensor (if damaged or codes present) × 1 — Motorcraft DY-1430 or equivalent

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure exhaust system is completely cool to the touch (wait at least 2 hours after engine operation)
3. Disconnect negative battery terminal to prevent O2 sensor codes during removal
4. Raise vehicle securely on jack stands at manufacturer-specified lift points
5. Spray all exhaust flange bolts, hanger bolts, and O2 sensor threads with penetrating oil and allow to soak for 15-30 minutes
6. Locate the catalytic converter requiring replacement (driver or passenger side based on diagnostic codes)

Procedure

1. 1

   Disconnect oxygen sensors
   Locate the upstream and downstream oxygen sensors on the catalytic converter. Disconnect the electrical connectors by pressing the release tab and pulling apart. Use the oxygen sensor socket to carefully remove both sensors by turning counterclockwise. If sensors are seized, apply additional penetrating oil and use a breaker bar for leverage. Inspect sensor threads and replace sensors if damaged.
2. 2

   Remove heat shield bolts
   Remove the heat shield bolts securing the catalytic converter heat shield using the appropriate socket. The 3.5L EcoBoost typically has 3-4 heat shield bolts per converter. Set heat shield aside. Inspect bolts for damage and replace if threads are stripped.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
3. 3

   Disconnect upstream exhaust flange
   Locate the upstream flange connection between the turbocharger downpipe and catalytic converter. Remove the exhaust flange bolts using a socket and ratchet. There are typically 3 bolts in a triangular pattern. Support the catalytic converter weight with one hand or have an assistant support it to prevent strain on downstream connections. Remove and discard the old gasket.
   ⚠The turbocharger downpipe is fragile. Do not allow the catalytic converter to hang unsupported, as this can damage the turbo outlet flange.
   Torque spec

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

   Disconnect downstream exhaust flange
   Locate the downstream flange connection between the catalytic converter and mid-pipe. Remove the flange bolts (typically 2-3 bolts). Keep the catalytic converter supported throughout this process. Remove and discard the old gasket. Clean the flange surfaces with a wire brush if needed.
   Torque spec

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

   Remove exhaust hanger support
   Locate the rubber exhaust hanger(s) supporting the catalytic converter assembly. Remove the hanger bolts or use a pry tool to carefully separate the exhaust pipe from the rubber isolators. The 3.5L EcoBoost typically has 1-2 hangers per catalytic converter section. Avoid tearing the rubber isolators if they will be reused.
   Torque spec

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

   Remove catalytic converter
   With all connections disconnected, carefully lower the catalytic converter assembly from the vehicle. Maneuver it past any obstructions such as frame rails or driveshaft. Inspect the turbocharger outlet and mid-pipe flanges for damage, cracks, or warping. Clean all flange surfaces thoroughly with a wire brush to ensure proper gasket sealing.
7. 7

   Prepare new catalytic converter
   Unpack the new direct-fit catalytic converter and verify it matches the original unit in flange locations and overall length. Install new flange gaskets on the upstream and downstream flanges. Apply a thin coat of nickel-based anti-seize to all exhaust flange bolt threads (not the bolt heads).
8. 8

   Install new catalytic converter
   Carefully position the new catalytic converter into place, aligning the upstream flange with the turbocharger downpipe first. Support the converter weight while aligning the downstream flange with the mid-pipe. Ensure both flanges are properly seated with gaskets in position before installing any bolts.
9. 9

   Install and torque upstream flange bolts
   Hand-thread all upstream exhaust flange bolts to prevent cross-threading. Once all bolts are started, tighten them in a star or cross pattern to ensure even gasket compression. Torque to specification using a torque wrench. Apply anti-seize to threads as specified.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
10. 10

    Install and torque downstream flange bolts
    Hand-thread all downstream flange bolts. Tighten in a cross pattern to ensure even gasket compression. Torque to specification using a torque wrench. Apply anti-seize as specified in torque specs.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
11. 11

    Reinstall exhaust hangers
    Reconnect the exhaust hanger supports by installing hanger bolts or pressing the exhaust pipe back into the rubber isolators. Ensure the exhaust system hangs naturally without binding or excessive tension. Torque hanger bolts to specification.
    Torque spec

    Hanger Bolts23 Nm (17 lb-ft)
12. 12

    Install oxygen sensors
    Apply a small amount of anti-seize compound to the oxygen sensor threads only (avoid getting anti-seize on the sensor tip). Thread each oxygen sensor into the catalytic converter by hand to prevent cross-threading. Use the oxygen sensor socket and torque wrench to tighten to specification. Reconnect the electrical connectors to both upstream and downstream sensors, ensuring they click into place securely.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
13. 13

    Reinstall heat shield
    Position the heat shield over the catalytic converter. Install all heat shield bolts and torque to specification. Ensure the heat shield does not contact any part of the catalytic converter body to prevent rattling.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Reconnect the negative battery terminal
2. Lower the vehicle from jack stands
3. Double-check all exhaust connections are tight and no tools were left under the vehicle
4. Verify all oxygen sensor connectors are fully seated and secured

Verification

• Start the engine and listen for exhaust leaks at all flange connections. A hissing sound indicates a leak that must be corrected
• Allow engine to reach operating temperature and verify no exhaust smell is entering the cabin
• Check for exhaust leaks with engine at idle and at 2000 RPM
• Use an OBD-II scanner to clear any stored catalytic converter or oxygen sensor codes
• After clearing codes, drive the vehicle through several drive cycles (city and highway) to allow the PCM to verify proper catalytic converter function
• Re-scan for codes after 50-100 miles of driving to confirm no catalytic efficiency codes return
• Visually inspect all connections after the first drive for any signs of exhaust soot indicating leaks

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