This procedure covers the removal and replacement of the downpipes on a 2015-2020 Ford F-150 with the 3.5L EcoBoost engine, including disconnecting oxygen sensors and exhaust components.

Warnings

Tools required

Parts

• Downpipe gaskets (turbo to downpipe) × 2 — Use OEM specification
• Exhaust flange gasket (downpipe to mid-pipe) × 1 — Use OEM specification
• Replacement downpipes (if not reusing) × 2 — Aftermarket or OEM

Preparation

1. Park vehicle on level surface and apply parking brake. Place wheel chocks behind rear wheels.
2. Allow exhaust system to cool completely if vehicle has been recently operated.
3. Apply penetrating oil to all exhaust fasteners, oxygen sensor threads, and hanger bolts. Allow to soak for at least 30 minutes or preferably overnight.
4. Raise front of vehicle using floor jack and support securely on jack stands rated for vehicle weight.
5. Disconnect negative battery terminal to prevent oxygen sensor fault codes during removal.
6. Spray additional penetrating oil on all fasteners immediately before beginning removal.

Procedure

1. 1

   Remove heat shields
   Locate and remove the heat shields covering the downpipes and turbochargers. These are secured with multiple bolts around the perimeter. Remove all heat shield bolts and carefully lower the shields away from the work area. Some shields may have multiple sections.
   Torque spec

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

   Disconnect oxygen sensors
   Locate all four oxygen sensors (two upstream near turbos, two downstream on downpipes). Disconnect the electrical connectors by pressing the release tabs. Using an oxygen sensor socket or 22mm offset wrench, carefully unthread each sensor. Work slowly to avoid breaking the sensors in the bungs. Set sensors aside in a clean area to protect the tips.
   ⚠Oxygen sensors are fragile and expensive. Do not drop or contaminate the sensor tips. If sensors are seized, apply heat carefully to the bung, not the sensor itself.
   Torque spec

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

   Remove driver side downpipe to mid-pipe connection
   Locate the flange connection where the driver side downpipe connects to the mid-pipe. Support the mid-pipe with a jack or secure support. Remove the exhaust flange bolts at this connection. You may need to apply additional penetrating oil and use a breaker bar if bolts are corroded. Separate the flange using a pry bar if necessary.
   ⚠Support the exhaust system to prevent sudden movement when disconnecting flanges. The mid-pipe and rear exhaust are heavy.
   Torque spec

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

   Remove passenger side downpipe to mid-pipe connection
   Locate the flange connection where the passenger side downpipe connects to the mid-pipe. Remove the exhaust flange bolts at this connection. Once both downpipe connections are separated, the mid-pipe and rear exhaust assembly can be lowered slightly for additional clearance.
   Torque spec

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

   Disconnect exhaust hangers
   Locate the rubber exhaust hangers supporting the downpipes. Use an exhaust hanger removal tool or carefully pry the hangers off their mounting studs using a pry bar. Work the rubber isolators off the studs by pulling and twisting. There are typically 2-3 hangers per downpipe.
6. 6

   Remove driver side downpipe to turbo connection
   Access the flange bolts connecting the driver side downpipe to the turbocharger outlet. These are located high in the engine bay. Remove all flange bolts securing the downpipe to the turbo. Note the position of any brackets or supports. Carefully work the downpipe free from the turbo flange and lower it from the vehicle.
   ⚠Downpipes are heavy and awkward to maneuver. Have an assistant help guide the pipe out to avoid damaging other components or dropping the pipe.
   Torque spec

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

   Remove passenger side downpipe to turbo connection
   Access the flange bolts connecting the passenger side downpipe to the turbocharger outlet. Remove all flange bolts securing the downpipe to the turbo. Note the position of any brackets or supports. Carefully work the downpipe free from the turbo flange and lower it from the vehicle.
   Torque spec

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

   Clean and inspect mating surfaces
   With downpipes removed, clean all exhaust flange mating surfaces using a wire brush and scraper. Remove all old gasket material from the turbo outlet flanges and the mid-pipe connection flanges. Inspect all studs and threads for damage. Clean oxygen sensor bungs with a thread chaser or tap if installing new sensors.
   ℹ️Inspect removed downpipes for cracks, excessive corrosion, or damage. Check for carbon buildup that may indicate oil consumption or turbo seal issues.
9. 9

   Install new gaskets and position driver side downpipe
   Install a new gasket on the driver side turbo outlet flange. Apply a thin coat of anti-seize to the flange bolt threads only (not to gasket surfaces). Position the new or cleaned downpipe to the turbo flange, ensuring proper alignment. Start all flange bolts by hand before tightening any of them.
   ℹ️Do not use exhaust sealant on turbo gaskets. The high temperatures can cause gaskets to fail prematurely.
10. 10

    Torque driver side downpipe to turbo connection
    Tighten the flange bolts securing the driver side downpipe to the turbocharger in a cross-pattern to ensure even gasket compression. Torque all bolts to specification using a torque wrench.
    Torque spec

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

    Install and torque passenger side downpipe to turbo
    Install a new gasket on the passenger side turbo outlet flange. Apply anti-seize to bolt threads. Position the downpipe to the turbo flange and start all bolts by hand. Tighten the flange bolts in a cross-pattern and torque to specification.
    Torque spec

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

    Reconnect downpipes to mid-pipe
    Install new exhaust flange gasket(s) at the downpipe to mid-pipe connection points. Raise the mid-pipe assembly into position and align with both downpipe flanges. Apply anti-seize to exhaust flange bolt threads. Start all bolts by hand, then tighten in a cross-pattern and torque to specification.
    Torque spec

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

    Reinstall exhaust hangers
    Reattach all rubber exhaust hangers to their mounting studs. Ensure the exhaust system hangs evenly and has proper clearance from the chassis, driveshaft, and other components. Adjust hanger positions if necessary to achieve proper alignment.
14. 14

    Reinstall oxygen sensors
    Apply a small amount of anti-seize compound to the oxygen sensor threads only. Do not get anti-seize on the sensor tips. Thread each sensor into its bung by hand until snug, then torque to specification using an oxygen sensor socket. Reconnect all electrical connectors, ensuring they click into place securely.
    ⚠Use anti-seize sparingly on oxygen sensor threads. Excess anti-seize can contaminate the sensor and cause false readings.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
15. 15

    Reinstall heat shields
    Position all heat shields back in their original locations. Ensure shields are properly seated and not touching moving components. Install and torque all heat shield bolts to specification.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Reconnect negative battery terminal.
2. Lower vehicle from jack stands.
3. Double-check that all tools and parts have been removed from under the vehicle.

Verification

• Start the engine and listen for exhaust leaks at all flange connections. A slight hissing sound indicates a leak that must be corrected.
• Check for exhaust leaks using a flashlight while engine is running. Look for visible exhaust gases escaping from connections.
• Allow engine to reach operating temperature and verify no unusual noises, vibrations, or rattles from the exhaust system.
• Verify all oxygen sensor readiness monitors complete using an OBD-II scanner. This may require a drive cycle.
• Visually inspect exhaust system clearances while engine is running to ensure no contact with chassis or driveline components due to heat expansion.
• Check for warning lights on the instrument cluster. Clear any stored codes related to oxygen sensor disconnection if they do not clear automatically.

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