Intake Manifold Gasket

This procedure covers removal and replacement of the intake manifold gasket on the 2016-2021 Honda Civic 1.5L turbocharged engine, including removal of associated components and proper reassembly with torque specifications.

Warnings

Tools required

Parts

• Intake manifold gasket × 1 — Use OEM specification
• Throttle body gasket × 1 — Use OEM specification
• PCV valve O-ring × 1 — Use OEM specification
• Coolant (if drained) × 1 — Honda Type 2 Coolant

Fluids

• Honda Type 2 Coolant (Blue) — 2 qt

Preparation

1. Park vehicle on level surface and allow engine to cool completely (minimum 2 hours)
2. Disconnect negative battery terminal and wait 3 minutes
3. Remove engine cover by pulling upward on front edge, then lifting off
4. Place drain pan under vehicle and drain coolant from radiator petcock and engine block drain
5. Relieve fuel system pressure by removing fuel pump fuse and cranking engine until it stops
6. Gather all tools, new gaskets, and coolant before beginning disassembly

Procedure

1. 1

   Remove air intake system
   Disconnect the mass airflow sensor electrical connector. Loosen the clamp at the turbocharger inlet and remove the air intake duct and air filter housing assembly as a unit. Remove the engine cover mounting brackets if they interfere with access.
2. 2

   Disconnect throttle body connections
   Disconnect the throttle body electrical connector. Remove any vacuum hoses or PCV hoses connected to the throttle body. Label each connection for reassembly. Remove the four throttle body mounting bolts and carefully separate the throttle body from the intake manifold. Set aside with gasket.
   ℹ️Do not force throttle body off. If stuck, gently twist while pulling to break gasket seal.
   Torque spec

   Throttle Body Bolts10 Nm (7 lb-ft)
3. 3

   Remove fuel rail assembly
   Disconnect the fuel injector electrical connectors (four connectors). Using the appropriate fuel line disconnect tool, carefully disconnect the fuel supply line from the fuel rail. Remove the two fuel rail mounting bolts. Gently pull the fuel rail with injectors straight up and out of the intake manifold. Cap or cover injector ports in intake manifold immediately.
   ⚠Have rags ready to catch residual fuel. Keep away from ignition sources.
   Torque spec

   Fuel Rail Bolts12 Nm (9 lb-ft)
4. 4

   Disconnect PCV system and vacuum lines
   Remove the PCV valve from the intake manifold by turning counterclockwise. Disconnect all vacuum hoses from the intake manifold including brake booster hose, EVAP purge valve hose, and any other vacuum connections. Label each hose with tape and marker noting its position.
   ℹ️Take photos of vacuum hose routing before removal for reference during reassembly.
5. 5

   Remove EGR valve if equipped
   Disconnect the EGR valve electrical connector. Disconnect any coolant hoses to the EGR valve (mark positions). Remove the EGR valve mounting bolts and remove the valve assembly from the intake manifold or cylinder head. Plug any open coolant passages.
6. 6

   Disconnect coolant crossover and remaining connections
   Locate the coolant crossover pipe on the rear of the intake manifold. Disconnect coolant hoses and remove coolant crossover bolts if equipped. Disconnect any remaining electrical connectors, vacuum lines, or breather hoses attached to the intake manifold. Ensure all connections are freed before attempting manifold removal.
7. 7

   Remove intake manifold mounting bolts
   Starting from the outer bolts and working toward the center, evenly loosen all intake manifold mounting bolts in a crisscross pattern. Remove all bolts completely and keep them organized. Note the location of any brackets or ground wires attached to manifold bolts for proper reinstallation.
   ⚠Do not pry against sealing surfaces. If manifold is stuck, tap gently with plastic mallet at mounting bosses only.
   Torque spec

   Intake Manifold Bolts25 Nm (18 lb-ft)
8. 8

   Remove intake manifold
   Carefully lift the intake manifold straight up and away from the cylinder head. Wiggle gently if needed but do not pry. Once free, immediately cover the cylinder head intake ports with clean rags or tape to prevent debris entry. Place the manifold on a clean work surface.
9. 9

   Clean gasket surfaces
   Using a plastic gasket scraper, carefully remove all old gasket material from both the intake manifold mating surface and the cylinder head surface. Do not use metal scrapers that could damage aluminum surfaces. Clean surfaces thoroughly with brake cleaner and lint-free rags. Inspect both surfaces for warping, cracks, or damage. Surfaces must be completely clean and dry before installing new gasket.
   ⚠️Ensure no gasket material, debris, or cleaning solution enters the intake ports or combustion chambers. Foreign material will cause engine damage.
10. 10

    Install new intake manifold gasket
    Position the new intake manifold gasket on the cylinder head, ensuring all port openings align correctly. The gasket should fit over alignment dowels if present. Do not use gasket sealer unless specifically required by the gasket manufacturer. Verify gasket is seated properly before proceeding.
11. 11

    Install intake manifold
    Carefully lower the intake manifold onto the cylinder head, aligning it with the new gasket and any dowel pins. Insert all mounting bolts finger-tight, ensuring any brackets or ground wires are reinstalled in their original positions. Hand-tighten all bolts before proceeding to torque.
12. 12

    Torque intake manifold bolts
    Using a torque wrench, tighten the intake manifold bolts in the proper sequence starting from the center bolts and working outward in a crisscross pattern. Torque all bolts to specification in at least two progressive steps: first to 12 Nm, then to final specification. This ensures even gasket compression and proper sealing.
    ⚠Follow the tightening sequence precisely from center outward. Improper sequence can warp the manifold or cause vacuum leaks.
    Torque spec

    Intake Manifold Bolts25 Nm (18 lb-ft)
13. 13

    Reinstall coolant crossover and EGR valve
    If equipped, reinstall the coolant crossover pipe with new O-rings and torque bolts to specification. Reinstall the EGR valve with a new gasket if required, torque to specification, reconnect coolant hoses, and electrical connector. Ensure all connections are secure.
14. 14

    Reinstall PCV valve and vacuum lines
    Install the PCV valve with new O-ring into the intake manifold and torque to specification. Reconnect all vacuum hoses to their original positions using your labels and photos as reference. Ensure all hoses are fully seated and clamps are properly positioned.
15. 15

    Reinstall fuel rail assembly
    Remove covers from intake manifold injector ports. Lubricate injector O-rings lightly with clean engine oil. Carefully align all four injectors with their ports and press the fuel rail assembly straight down until injectors are fully seated. Install and torque fuel rail bolts to specification. Reconnect the fuel supply line until it clicks into place. Reconnect all four injector electrical connectors.
    ⚠Ensure injectors are aligned properly before applying pressure. Forcing misaligned injectors will damage O-rings and cause fuel leaks.
    Torque spec

    Fuel Rail Bolts12 Nm (9 lb-ft)
16. 16

    Reinstall throttle body
    Install a new throttle body gasket on the intake manifold. Position the throttle body and install all four mounting bolts. Torque bolts to specification in a crisscross pattern. Reconnect the throttle body electrical connector and any vacuum or PCV hoses that were removed.
    Torque spec

    Throttle Body Bolts10 Nm (7 lb-ft)
17. 17

    Reinstall air intake system and refill coolant
    Reinstall the air filter housing and intake duct assembly. Reconnect the mass airflow sensor connector and tighten the turbocharger inlet clamp. Refill the cooling system with Honda Type 2 coolant to the proper level. Reconnect the negative battery terminal. Install engine cover.

Reassembly

1. Double-check that all electrical connectors, vacuum hoses, and fuel lines are properly connected
2. Verify all bolts are torqued to specification and no tools or rags are left in the engine bay
3. Ensure coolant is filled to proper level and radiator cap is secure

Verification

• Turn ignition to ON position (do not start) and check for fuel leaks around fuel rail and supply line
• Start engine and allow to reach operating temperature while monitoring for coolant leaks, vacuum leaks (rough idle), or abnormal noises
• Check for any warning lights on dashboard, particularly check engine light
• Verify smooth idle and proper throttle response with no hesitation
• After test drive, recheck coolant level when engine is cool and top off if necessary
• Inspect all connection points for leaks after first drive cycle

Related trouble codes on this vehicle

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

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