This procedure covers the removal and installation of the rear exhaust pipe section on a 2021-2024 Ford F-150 with the 3.5L EcoBoost V6 engine, including disconnecting hangers, flanges, and oxygen sensors.

Warnings

Tools required

Parts

• Rear exhaust pipe section × 1 — Use OEM specification
• Exhaust flange gasket × 1 — Use OEM specification
• Exhaust hanger insulators (if damaged) × 2 — Use OEM specification

Preparation

1. Ensure engine and exhaust system are completely cool to the touch
2. Park vehicle on level, stable ground and apply parking brake
3. Spray all exhaust flange bolts, hanger bolts, and oxygen sensor threads with penetrating oil and allow to soak for 15-30 minutes
4. Raise vehicle using floor jack and support securely on jack stands at manufacturer-specified lift points
5. Verify adequate clearance to access rear exhaust section from underneath vehicle

Procedure

1. 1

   Disconnect oxygen sensor electrical connector
   Locate the downstream oxygen sensor on the rear exhaust section. Press the locking tab and disconnect the electrical connector. Route the wiring away from the work area and secure to prevent damage during removal.
2. 2

   Remove downstream oxygen sensor
   Using the oxygen sensor socket, carefully remove the downstream O2 sensor from the rear exhaust pipe. Turn counterclockwise and remove completely. Inspect sensor condition and threads. If reusing, protect sensor from damage and contamination.
   ⚠Oxygen sensors are fragile. Avoid dropping or contaminating the sensor tip with oil or grease as this will cause sensor failure.
   Torque spec

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

   Support rear exhaust section
   Position a floor jack with a block of wood under the rear muffler section to support the weight of the rear exhaust assembly. Raise jack just enough to take the weight off the hangers without applying upward pressure.
4. 4

   Remove heat shield fasteners (if equipped)
   If heat shields are present over the rear exhaust section or near the flange connection, remove the retaining bolts using a 10mm socket. Set heat shields and hardware aside for reinstallation.
   Torque spec

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

   Disconnect exhaust hangers
   Locate the rubber exhaust hanger insulators supporting the rear exhaust section (typically 2 hangers). Using a pry bar or exhaust hanger removal tool, carefully pry the exhaust pipe loops out of the rubber hanger insulators. Work methodically to avoid tearing the rubber insulators. Inspect insulators for cracking or deterioration and replace if damaged.
   ⚠Exhaust hangers are under tension. Control the exhaust pipe when releasing hangers to prevent sudden movement.
6. 6

   Remove flange connection bolts
   Locate the flange connection between the rear exhaust section and the mid-pipe section. Using a 15mm socket, remove the flange bolts (typically 2 bolts). Support the rear section with the jack as you remove the final bolts. Keep track of any springs, washers, or retaining hardware.
   ⚠Flange bolts may be severely corroded. If a bolt breaks, the remaining stud will need to be extracted before installation.
   Torque spec

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

   Remove rear exhaust section
   With all fasteners removed and hangers disconnected, carefully lower the jack and remove the rear exhaust section from under the vehicle. Remove and discard the old flange gasket. Maneuver the section carefully to avoid contact with brake lines, fuel lines, or wiring.
8. 8

   Clean flange surfaces and inspect threads
   Using a wire brush, thoroughly clean the mating flange surface on the mid-pipe section. Remove all old gasket material, rust, and debris to ensure a proper seal. Inspect flange bolt threads and clean with a wire brush. Chase threads with a tap if necessary. Verify all mounting points and hanger brackets are secure and undamaged.
9. 9

   Install new rear exhaust section
   Position the new flange gasket onto the mid-pipe flange. Apply anti-seize compound to the flange bolt threads as specified. Raise the new rear exhaust section into position using the floor jack. Align the flange connection and start flange bolts by hand to ensure proper thread engagement. Do not fully tighten at this stage.
10. 10

    Install exhaust hangers
    With the rear section supported by the jack, align the exhaust pipe loops with the rubber hanger insulators. Use a pry bar or hanger tool to lever the loops into the insulators. Ensure all hangers are fully seated and secure.
11. 11

    Torque flange bolts
    Using a torque wrench, tighten the flange bolts in a cross-pattern to the specified torque value. This ensures even loading on the flange and proper gasket seating. Verify the exhaust section is properly aligned and not contacting the frame, fuel tank, or suspension components. Adjust hanger position if needed before final torquing.
    Torque spec

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

    Install downstream oxygen sensor
    Apply a thin coating of anti-seize compound to the oxygen sensor threads only, being extremely careful to avoid getting any compound on the sensor tip. Thread the O2 sensor into the bung by hand until snug, then torque to specification using the oxygen sensor socket and torque wrench.
    Torque spec

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

    Reconnect oxygen sensor electrical connector
    Route the oxygen sensor wiring properly to avoid contact with hot exhaust components or moving parts. Connect the electrical connector to the sensor and verify the locking tab clicks into place securely.
14. 14

    Reinstall heat shields
    If heat shields were removed, position them back in their original locations and install the retaining bolts. Torque heat shield bolts to specification. Ensure shields are not contacting the exhaust pipe or creating any rattle points.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Verify all fasteners are torqued to specification and no tools or parts are left under the vehicle
2. Check that exhaust system has adequate clearance from frame, suspension, body panels, and fuel system components throughout its length
3. Ensure oxygen sensor wiring is properly routed and secured away from heat and moving parts

Verification

• Lower vehicle from jack stands and remove all support equipment
• Start engine and listen for exhaust leaks at the flange connection and oxygen sensor bung. A hissing sound indicates a leak that must be corrected
• With engine running, visually inspect the flange connection and O2 sensor for any signs of exhaust gas leakage
• Rev engine to 2000-3000 RPM and verify no abnormal sounds, vibrations, or rattles from the exhaust system
• Allow engine to reach operating temperature and recheck for leaks. Some minor seepage may disappear as gaskets seat with heat
• Take a short test drive and verify no exhaust odors in cabin, no rattles or contact noises, and check engine light does not illuminate for oxygen sensor codes
• After test drive, perform a final visual inspection of all connections and verify exhaust hangers remain properly seated

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