This procedure covers the removal and replacement of the intermediate pipe (center exhaust pipe section) on the 2018-2024 Honda Accord 1.5L Turbo engine.

Warnings

Tools required

Parts

• Intermediate pipe assembly × 1 — Use OEM specification
• Exhaust flange gaskets × 2 — Use OEM specification
• Exhaust flange bolts (if corroded) × 4 — M10 x 1.25 x 35mm

Preparation

1. Ensure engine and exhaust system are completely cool to the touch
2. Park vehicle on level surface and engage parking brake
3. Raise front of vehicle and support securely on jack stands rated for vehicle weight
4. Spray all exhaust flange bolts, hanger bolts, and heat shield bolts with penetrating oil and allow to soak for 15-30 minutes

Procedure

1. 1

   Remove heat shields
   Locate and remove any heat shields covering the intermediate pipe connections. Remove bolts securing heat shields using 10mm socket. Set shields and hardware aside for reinstallation.
   Torque spec

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

   Disconnect oxygen sensor (if equipped on intermediate pipe)
   Locate the oxygen sensor electrical connector on the intermediate pipe section. Unplug the connector by pressing the release tab and pulling apart. If removing sensor from pipe, use 22mm oxygen sensor socket to carefully unthread sensor, turning counterclockwise. Keep sensor clean if reusing.
   ⚠Oxygen sensor threads are delicate. Do not force or cross-thread during removal or installation.
   Torque spec

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

   Remove front flange connection
   Locate the front flange connection between the downpipe/catalytic converter and intermediate pipe. Using 14mm socket, remove the two flange bolts holding this connection. Support the intermediate pipe weight to prevent it from hanging on rear connection. Separate the flanges and remove old gasket.
   Torque spec

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

   Disconnect rubber exhaust hangers
   Locate the rubber exhaust hangers supporting the intermediate pipe (typically 2-3 hangers). Use a pry bar or exhaust hanger tool to carefully pop the exhaust hanger rods out of the rubber isolators. Work methodically to avoid tearing rubber mounts.
   ℹ️Lubricating hanger rods with soapy water can ease removal and installation.
   Torque spec

   Hanger Bolts19 Nm (14 lb-ft)
5. 5

   Remove rear flange connection
   Locate the rear flange connection between the intermediate pipe and rear muffler section. Using 14mm socket, remove the two flange bolts holding this connection. Lower the intermediate pipe from the vehicle. Remove and discard old flange gasket.
   Torque spec

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

   Clean flange surfaces
   Use wire brush to thoroughly clean both mating flange surfaces on the front downpipe and rear muffler sections. Remove all old gasket material, carbon deposits, and corrosion to ensure proper seal with new gaskets.
7. 7

   Prepare new intermediate pipe
   Unpack new intermediate pipe and inspect for shipping damage. If reusing oxygen sensor, apply anti-seize compound to threads only (avoid sensor tip). Thread sensor into new pipe hand-tight, then torque to specification using oxygen sensor socket.
   ⚠Never apply anti-seize or lubricant to oxygen sensor tip as this will contaminate the sensor element.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
8. 8

   Install new flange gaskets
   Position new exhaust flange gaskets on both the front and rear flange connections. Ensure gaskets are properly aligned with bolt holes and flange surfaces.
9. 9

   Position intermediate pipe
   Carefully lift new intermediate pipe into position. Align the front flange with the downpipe/catalytic converter flange and the rear flange with the muffler section flange. Support pipe weight to maintain alignment.
10. 10

    Install front flange bolts
    Apply anti-seize compound to the threads of new or reused front flange bolts. Insert both bolts through the front flange connection and thread by hand. Do not fully tighten yet to allow for alignment adjustment.
    Torque spec

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

    Install rear flange bolts
    Insert both rear flange bolts through the rear flange connection and thread by hand. Ensure intermediate pipe is positioned properly and gaskets have not shifted. Do not fully tighten yet.
    Torque spec

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

    Reinstall rubber exhaust hangers
    Align the intermediate pipe hanger rods with the rubber isolators on the vehicle body. Push each rod into its corresponding rubber mount, ensuring full seating. This may require adjusting pipe position slightly.
    Torque spec

    Hanger Bolts19 Nm (14 lb-ft)
13. 13

    Torque flange bolts
    Using torque wrench, tighten the front flange bolts to specification in a cross-pattern. Then torque the rear flange bolts to specification in the same manner. Verify pipe alignment and that there is no binding or stress on connections.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
14. 14

    Reconnect oxygen sensor connector
    Locate the oxygen sensor electrical connector and route wiring to avoid contact with hot exhaust components. Connect the sensor plug until it clicks into place. Ensure connector is fully seated and locking tab engaged.
15. 15

    Reinstall heat shields
    Position heat shields over the intermediate pipe and flange connections. Install and torque heat shield bolts to specification. Ensure shields do not contact moving components or create rattles.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Double-check all flange bolts are torqued to specification
2. Verify all rubber exhaust hangers are properly seated
3. Ensure oxygen sensor connector is fully engaged and wiring is routed safely away from hot surfaces
4. Confirm heat shields are secure and not contacting other components

Verification

• Lower vehicle from jack stands and start engine
• Listen carefully for exhaust leaks at both flange connections while engine idles
• Perform visual inspection underneath vehicle for any signs of exhaust gas leaking from connections
• Allow engine to reach operating temperature and verify no abnormal exhaust smells in cabin
• Take brief test drive and listen for any rattles, vibrations, or exhaust leaks under acceleration
• Check that no exhaust warning lights or oxygen sensor codes appear on instrument cluster

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