This procedure covers the removal and replacement of the downpipe/catalytic converter assembly on a 2015-2020 Ford F-150 with the 5.0L Coyote V8 engine, including oxygen sensor removal and exhaust component disconnection.

Warnings

Tools required

Parts

• Downpipe/Catalytic Converter Assembly × 1 — Use OEM specification or aftermarket equivalent
• Exhaust flange gaskets × 2 — Use OEM specification
• Exhaust manifold to downpipe gasket × 1 — Use OEM specification
• Oxygen sensor (if damaged) — As needed - upstream and downstream

Preparation

1. Park vehicle on level surface and allow exhaust system to cool completely (minimum 2 hours)
2. Disconnect negative battery terminal to prevent O2 sensor fault codes during removal
3. Raise vehicle and secure on jack stands rated for vehicle weight, minimum 24 inches of clearance recommended
4. Spray all exhaust fasteners with penetrating oil and allow to soak for 15-30 minutes
5. Locate and identify upstream (pre-cat) and downstream (post-cat) oxygen sensors on downpipe assembly

Procedure

1. 1

   Remove oxygen sensors
   Disconnect electrical connectors from both upstream and downstream oxygen sensors by pressing the release tab and pulling apart. Using a 22mm oxygen sensor socket, turn sensors counterclockwise to remove. The upstream sensor is located before the catalytic converter, downstream sensor after. If sensors are seized, apply heat carefully with a propane torch to the bung area only, avoiding the sensor body and wiring.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
2. 2

   Remove heat shields
   Remove heat shields covering the downpipe assembly using appropriate socket. These may be attached to the transmission crossmember or underbody. Note the orientation and mounting points for reinstallation. Some shields may have multiple sections.
   Torque spec

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

   Support downpipe assembly
   Position a floor jack with a block of wood under the downpipe assembly to support its weight during removal. Raise jack until it just contacts the pipe but does not lift the vehicle. This will prevent the heavy assembly from falling when disconnected.
4. 4

   Disconnect from exhaust manifolds
   Locate the dual connection points where the downpipe connects to both exhaust manifolds. Remove the manifold nuts at these flanges using an 18mm socket. There are typically 2-3 nuts per side. The passenger side may require working around the starter. Remove and discard the old gaskets.
   ⚠Studs may break if corroded. Do not force. Apply additional penetrating oil and allow to soak if resistance is excessive.
   Torque spec

   Manifold Nuts42 Nm (31 lb-ft)
5. 5

   Disconnect exhaust hangers
   Locate rubber exhaust hangers supporting the downpipe assembly. These are typically located mid-pipe and toward the rear connection. Use a pry bar to carefully separate the hanger loops from the mounting brackets. Spray with silicone lubricant if tight.
   Torque spec

   Hanger Bolts26 Nm (19 lb-ft)
6. 6

   Disconnect from mid-pipe
   Locate the flange connection where the downpipe connects to the mid-pipe section (approximately below the transmission). Remove the flange bolts using a 15mm socket. There are typically 2-4 bolts at this connection. Support the mid-pipe to prevent it from dropping.
   Torque spec

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

   Remove downpipe assembly
   With all connections disconnected, carefully lower the floor jack while guiding the downpipe assembly down and toward the rear of the vehicle. The assembly will need to be maneuvered around the transmission crossmember and driveshaft. Tilt and rotate as necessary to clear all obstructions. Remove assembly from under vehicle.
   ⚠Assembly weighs 30-40 lbs and has sharp edges. Use gloves and control descent carefully.
8. 8

   Clean mating surfaces
   Using a wire brush and scraper, thoroughly clean all exhaust flange mating surfaces at the manifold connections and mid-pipe connection. Remove all old gasket material, carbon deposits, and rust. Inspect studs for damage and replace if threads are damaged or studs are bent.
9. 9

   Install new downpipe assembly
   Apply anti-seize compound to all exhaust studs at manifold flanges and mid-pipe connection. Position new gaskets at all connection points. Lift the new downpipe assembly into position, supporting with floor jack. Align the manifold flanges first, then the mid-pipe connection. Start all fasteners hand-tight before final torquing.
10. 10

    Torque manifold connections
    Torque the manifold nuts at both exhaust manifold flanges in a crisscross pattern to ensure even gasket compression. Apply anti-seize to threads before installation.
    Torque spec

    Manifold Nuts42 Nm (31 lb-ft)
11. 11

    Torque mid-pipe connection
    Torque the flange bolts at the mid-pipe connection in a crisscross pattern. Apply anti-seize to bolt threads before installation.
    Torque spec

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

    Reinstall exhaust hangers
    Reconnect all rubber exhaust hangers to their mounting brackets. Use silicone spray if necessary. Ensure the exhaust system hangs evenly and does not contact the driveshaft, frame, or fuel tank. There should be at least 1/2 inch clearance to all components.
    Torque spec

    Hanger Bolts26 Nm (19 lb-ft)
13. 13

    Install oxygen sensors
    Apply a thin coat of anti-seize compound to the oxygen sensor threads only, keeping compound away from the sensor tip. Thread sensors in by hand first to avoid cross-threading, then torque to specification using oxygen sensor socket. Reconnect electrical connectors ensuring they click into place.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
14. 14

    Reinstall heat shields
    Reinstall all heat shields in their original positions. Ensure shields do not contact moving components or create vibration points.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Reconnect negative battery terminal
2. Lower vehicle from jack stands
3. Double-check all fastener torque values and electrical connections

Verification

• Start engine and allow to idle. Listen for any exhaust leaks at all connection points (manifolds and mid-pipe). A hissing sound indicates a leak.
• Visually inspect all connections for signs of exhaust gas escaping while engine is running
• Check that exhaust system hangs evenly with proper clearance from driveshaft, frame, and fuel tank (minimum 1/2 inch)
• Verify oxygen sensor readiness monitors complete after 50-100 miles of driving using OBD-II scanner
• Perform a test drive and listen for any rattles, vibrations, or exhaust noise indicating loose components

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