Exhaust Manifold

Remove and replace the exhaust manifold on a 2016-2021 Honda Civic 1.5L turbo, including turbocharger access and gasket replacement.

Warnings

Tools required

Parts

• Exhaust manifold gasket × 1 — Use OEM specification
• Exhaust manifold to downpipe gasket × 1 — Use OEM specification
• Heat shield gasket or seal (if equipped) × 1 — Use OEM specification
• O2 sensor (if damaged) × 1 — Use OEM specification
• Exhaust manifold nuts × 8 — Use OEM specification - often replace on removal

Fluids

• Honda Type 2 Coolant (Blue) — 1 qt

Preparation

1. Park vehicle on level surface and allow engine to cool completely for at least 3 hours
2. Disconnect negative battery terminal
3. Raise and support front of vehicle on jack stands
4. Remove engine undertray/splash shield
5. Drain approximately 2 quarts of coolant from radiator petcock into drain pan
6. Apply penetrating oil to all exhaust manifold nuts, heat shield bolts, and O2 sensor threads
7. Remove plastic engine cover if equipped

Procedure

1. 1

   Remove air intake components
   Disconnect the air intake tube from the turbocharger inlet. Remove the air filter box and intake duct assembly to gain access to the turbocharger and exhaust manifold area. Disconnect any vacuum lines or sensors attached to the intake system. Label connections for reassembly.
2. 2

   Disconnect turbocharger coolant lines
   Locate the coolant feed and return lines connected to the turbocharger. Place a drain pan underneath. Using a 10mm or 12mm wrench, carefully loosen and disconnect the coolant line fittings. Allow coolant to drain into pan. Cap or plug open lines to prevent contamination.
   ⚠Coolant lines use copper crush washers that should be replaced during reassembly.
3. 3

   Remove upstream oxygen sensor
   Locate the upstream O2 sensor in the exhaust manifold (pre-turbo location). Disconnect the electrical connector. Using an O2 sensor socket, carefully remove the sensor. If sensor is seized, apply heat and additional penetrating oil. Do not force to avoid thread damage.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
4. 4

   Disconnect turbocharger oil feed line
   Locate the oil feed line connected to the top of the turbocharger center housing. Place absorbent material underneath to catch residual oil. Remove the banjo bolt or fitting securing the oil feed line. Cap the turbocharger inlet to prevent contamination.
5. 5

   Remove heat shield
   Remove all heat shield mounting bolts securing the exhaust manifold heat shield. The shield may be in multiple pieces. Carefully remove the heat shield sections, noting their orientation for reinstallation. Some bolts access the manifold underneath the shield.
   ℹ️Heat shield bolts are often corroded. Use penetrating oil and expect potential breakage.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
6. 6

   Disconnect exhaust downpipe from turbocharger
   From underneath the vehicle, locate the flange connection between the turbocharger outlet and the exhaust downpipe. Remove the support hanger bolts if present. Remove the flange bolts connecting the downpipe to the turbocharger. Separate the connection and lower the downpipe away from the turbo outlet. Remove and discard the gasket.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)

   Hanger Bolts19 Nm (14 lb-ft)
7. 7

   Disconnect turbocharger oil return line
   From underneath, locate the oil return line from the bottom of the turbocharger to the engine block. Remove the bolts securing the oil return tube. Carefully separate the connection and allow residual oil to drain. Cap or plug openings to prevent contamination.
8. 8

   Remove exhaust manifold mounting nuts
   Working from the engine bay, locate all exhaust manifold mounting nuts (typically 8 nuts on studs). Using penetrating oil as needed, carefully remove all manifold nuts. Work from the hottest area (center cylinders) toward the cooler ends to reduce warping stress. If studs break, they will need to be extracted before reinstallation.
   ⚠Studs commonly break on this engine. Have stud extractor tools ready. Broken studs require drilling and extraction.
   Torque spec

   Exhaust Manifold Nuts30 Nm (22 lb-ft)
9. 9

   Remove exhaust manifold assembly
   With all fasteners removed, carefully work the exhaust manifold and integrated turbocharger assembly away from the cylinder head. The assembly is heavy and awkward. Maneuver it out through the top of the engine bay, being careful not to damage coolant lines, wiring, or other components. Remove and discard the old manifold gasket.
   ⚠Manifold with turbocharger attached weighs approximately 25-30 lbs. Use caution when lifting.
10. 10

    Clean mating surfaces
    Thoroughly clean the cylinder head exhaust port mating surface using a plastic scraper and wire brush. Remove all old gasket material without gouging the aluminum surface. Clean with brake cleaner and wipe dry. Inspect the surface for warping or damage. Clean the turbocharger outlet flange mating surface as well.
    ⚠Do not use metal scrapers on aluminum cylinder head surface. Use plastic scrapers only.
11. 11

    Install new exhaust manifold
    Position the new exhaust manifold gasket onto the cylinder head studs, ensuring proper alignment with exhaust ports. Carefully position the exhaust manifold and turbocharger assembly onto the studs and against the gasket. Start all manifold nuts by hand. Apply anti-seize compound to the nut threads. Torque nuts in a hot-to-cold sequence (center to ends) in multiple passes: first to 15 Nm, then to final specification.
    ℹ️Verify tightening sequence in factory service manual. Typically work from center cylinders outward.
    Torque spec

    Exhaust Manifold Nuts30 Nm (22 lb-ft)
12. 12

    Reconnect turbocharger oil return line
    Using a new gasket, reconnect the turbocharger oil return line to the bottom of the turbocharger and engine block. Install mounting bolts and torque to specification. Ensure proper sealing to prevent oil leaks.
    Torque spec

    Mounting Bolts45 Nm (33 lb-ft)
13. 13

    Reconnect exhaust downpipe
    Install a new gasket at the turbocharger outlet flange. Raise the exhaust downpipe into position and align with the turbocharger outlet. Apply anti-seize to flange bolt threads. Install and hand-tighten all flange bolts, then torque to specification in a cross pattern. Reconnect exhaust hanger bolts if removed.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)

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

    Reinstall oxygen sensor
    Apply anti-seize compound to the O2 sensor threads (avoid getting compound on the sensor tip). Thread the O2 sensor into the exhaust manifold by hand, then torque to specification using the O2 sensor socket. Reconnect the electrical connector.
    Torque spec

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

    Reconnect turbocharger oil and coolant lines
    Reconnect the turbocharger oil feed line using a new copper crush washer on the banjo bolt. Torque to specification. Reconnect the turbocharger coolant feed and return lines using new copper washers. Torque fittings to specification. Ensure all connections are secure and properly routed.
    ℹ️Always replace copper crush washers on oil and coolant line banjo bolts.
16. 16

    Reinstall heat shield and air intake
    Reinstall the heat shield sections in their original orientation. Install heat shield bolts and torque to specification. Reinstall the air intake system, air filter box, and intake tube. Reconnect all vacuum lines and sensors. Install engine undertray.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Refill cooling system with Honda Type 2 coolant to proper level
2. Check engine oil level and top off if necessary due to turbo oil line disconnection
3. Reconnect negative battery terminal
4. Double-check all fastener torque values and connection security
5. Verify no tools or materials left in engine bay

Verification

• Start engine and allow to idle. Listen for exhaust leaks at manifold and downpipe connections
• Monitor for oil leaks at turbocharger oil feed and return connections
• Check for coolant leaks at turbocharger coolant line connections
• Verify coolant level after engine reaches operating temperature and recheck after cooling
• Test drive vehicle and verify normal turbocharger boost operation and no abnormal exhaust sounds
• Recheck all fastener torque values after first heat cycle (50-100 miles)
• Inspect for exhaust discoloration around gasket areas after several drive cycles

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle