This procedure guides you through replacing a universal catalytic converter on a 2021-2024 Ford F-150 with the 3.5L EcoBoost V6 engine, including removal of the factory converter and installation of a welded or clamped universal unit.

Warnings

Tools required

Parts

• Universal catalytic converter (EPA or CARB compliant) × 1 — Match substrate size and cell count to OEM specs
• Exhaust flange gasket × 2 — Use OEM specification
• Oxygen sensor (if damaged during removal) × 1 — Motorcraft DY-1435 or equivalent
• Anti-seize compound (nickel-based) × 1 — High-temperature rated
• Exhaust hanger isolators (if deteriorated) × 2 — Use OEM specification

Preparation

1. Verify the vehicle has been off for at least 2 hours and exhaust system is completely cool to the touch
2. Park vehicle on level, solid ground and engage parking brake
3. Disconnect negative battery terminal to prevent oxygen sensor fault codes during repair
4. Raise vehicle using floor jack at factory jacking points and secure on jack stands rated for vehicle weight
5. Spray all exhaust flange bolts, oxygen sensor threads, and hanger bolts with penetrating oil and allow 15-20 minutes soak time
6. Identify which catalytic converter requires replacement (driver or passenger side bank)
7. Take photos of exhaust routing and hanger positions for reference during reassembly

Procedure

1. 1

   Disconnect oxygen sensors
   Locate the upstream and downstream oxygen sensors on the catalytic converter section being replaced. Disconnect the electrical connectors by pressing the release tabs. Using the oxygen sensor socket, carefully remove both sensors. Turn counterclockwise with steady pressure. If sensors are seized, apply heat carefully with propane torch around bung (not sensor itself) and retry. Inspect sensor threads and tips for damage.
   ⚠Oxygen sensors are fragile. Do not use excessive force or impact tools. If sensor breaks, you will need to extract the remaining portion from the bung.
2. 2

   Remove heat shields
   Remove any heat shields covering the catalytic converter section using appropriate socket for the heat shield bolts. Some shields may have multiple mounting points. Set shields aside for reinstallation. Inspect shield condition and replace if severely corroded or damaged.
   Torque spec

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

   Support exhaust system
   Position a transmission jack or exhaust jack under the exhaust pipe section to support weight during removal. Alternatively, use a wire or strap to support the rear exhaust section from the vehicle frame. This prevents exhaust system from dropping when hangers are disconnected.
4. 4

   Disconnect exhaust hangers
   Locate the rubber exhaust hanger isolators supporting the catalytic converter section. Use a pry bar or exhaust hanger removal tool to separate the exhaust hanger rods from the rubber isolators. Work carefully to avoid tearing the rubber. If isolators are cracked or deteriorated, plan to replace them during reassembly.
5. 5

   Remove upstream flange connection
   Locate the flange connection between the turbocharger downpipe and the catalytic converter inlet. Remove the flange bolts using appropriate socket. The connection may be a 2-bolt or 3-bolt flange depending on specific configuration. Once bolts are removed, carefully separate the flange joint. If gasket is stuck, use a pry bar in the flange gap to gently separate. Remove and discard old gasket.
   ⚠Flange may be seized due to heat cycling. Do not use excessive prying force that could damage flange faces.
   Torque spec

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

   Remove downstream flange connection
   Locate the flange connection between the catalytic converter outlet and the intermediate pipe or muffler section. Remove the flange bolts. Separate the flange joint and remove old gasket. If this is a slip-fit connection instead of a flange, note the insertion depth before separation for proper reinstallation alignment.
   Torque spec

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

   Remove catalytic converter assembly
   With both flange connections separated and hangers disconnected, carefully maneuver the catalytic converter assembly down and out from the vehicle. The twin-turbo configuration may make access tight. Rotate and angle the assembly as needed to clear suspension components, crossmembers, and frame rails. Lower the assembly to the ground.
8. 8

   Prepare pipes for universal converter
   Measure the factory catalytic converter overall length, inlet diameter, and outlet diameter. Determine cut points on the remaining exhaust pipes where the universal converter will be joined. Mark cut locations with soapstone or marker. Cut the existing pipes using reciprocating saw with metal blade or exhaust pipe cutter. Make cuts as straight as possible for best fit. Ensure adequate straight pipe remains on both sides for the universal converter connections (typically 2-3 inches minimum).
   ⚠Wear safety glasses and respirator when cutting. Secure pipes to prevent movement during cutting.
9. 9

   Clean pipe ends and test fit
   Use wire brush or abrasive disc to clean the cut pipe ends, removing all rust, scale, and carbon buildup. Clean back at least 3 inches from the cut edge. Test fit the universal catalytic converter between the pipes, verifying proper alignment and checking that oxygen sensor bungs will be positioned correctly (upstream sensor before converter, downstream sensor after converter). Adjust cut locations if necessary for proper positioning.
10. 10

    Install universal catalytic converter
    Position the universal converter between the pipe sections, ensuring proper flow direction (arrow marking on converter body). If welding, tack weld the converter in place at multiple points, verify alignment and hanger positions, then complete full circumference welds on both inlet and outlet joints. Allow welds to cool naturally. If using clamp-on method, slide band clamps onto pipes before positioning converter, then position converter and tighten clamps evenly to manufacturer specifications (typically 50-60 ft-lbs for band clamp bolts).
    ⚠️If welding, ensure adequate ventilation and remove all flammable materials from work area. Welding fumes are toxic.
11. 11

    Reconnect exhaust hangers
    Reconnect the exhaust hanger rods to the rubber isolators. Use lubricant or soapy water on the isolators to ease installation. Verify the exhaust system hangs at the correct height with proper clearance from the vehicle underbody, suspension components, and driveshaft. Adjust hanger positions if necessary.
12. 12

    Install oxygen sensors
    Apply a thin coat of nickel-based anti-seize compound to the oxygen sensor threads only, being extremely careful not to get any compound on the sensor tip. Thread sensors into their bungs by hand until snug, then tighten to specification using the oxygen sensor socket and torque wrench. Reconnect the electrical connectors ensuring they click securely into place.
    ⚠Anti-seize on sensor tip will destroy the sensor. Apply only to threads.
    Torque spec

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

    Reinstall heat shields
    Position the heat shields back in their original locations, ensuring they do not contact the exhaust pipes directly. Install and tighten heat shield bolts to specification. Verify shields have proper clearance and will not rattle.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Verify all exhaust connections are secure and properly torqued
2. Check that exhaust system has at least 1 inch clearance from all chassis components, suspension parts, fuel lines, and brake lines throughout full suspension travel
3. Reconnect negative battery terminal
4. Lower vehicle from jack stands

Verification

• Start engine and listen for exhaust leaks at all connection points. A slight ticking sound indicates a leak requiring immediate attention
• With engine running, carefully feel around all joints for escaping exhaust gas (use back of hand, not palm)
• Check for proper oxygen sensor operation by monitoring live data with scan tool. Both sensors should show voltage fluctuations once engine reaches operating temperature
• Clear any diagnostic trouble codes that may have set during the repair
• Test drive vehicle and verify normal acceleration and no check engine light illumination
• After 50-100 miles, re-inspect all connections and welds for any signs of leaks or failure. Re-torque band clamps if applicable

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