Intake Manifold

Remove and replace the intake manifold on the 2018-2024 Honda Accord 1.5L Turbo engine, including disconnection of fuel system, throttle body, and associated sensors.

Warnings

Tools required

Parts

• Intake manifold gasket × 1 — Use OEM specification
• Throttle body gasket × 1 — Use OEM specification
• PCV valve O-ring/seal × 1 — Use OEM specification
• Fuel injector O-rings (if disturbed) × 4 — Use OEM specification

Fluids

• Honda Type 2 Coolant (Blue) — 1 qt

Preparation

1. Ensure engine is completely cold (minimum 2 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Disconnect negative battery terminal and wait 3 minutes
4. Remove engine cover by pulling upward on cover (typically clips in place)
5. Relieve fuel system pressure: Remove fuel pump relay from under-hood fuse box, start engine and let it run until it stalls, then crank for 3 seconds
6. Reinstall fuel pump relay after pressure relief
7. Place drain pan under vehicle to catch any coolant spillage

Procedure

1. 1

   Disconnect air intake system
   Loosen clamp at air filter box and throttle body. Disconnect mass airflow sensor electrical connector. Remove entire air intake tube assembly from air filter box to throttle body. Remove air filter box if additional clearance is needed.
2. 2

   Disconnect throttle body and associated components
   Disconnect throttle body electrical connector. Label and disconnect all vacuum hoses attached to throttle body and intake manifold (brake booster, PCV, EVAP purge). Remove throttle body mounting bolts and carefully remove throttle body with gasket.
   ℹ️Do not allow debris to enter throttle body opening or intake manifold. Cover openings with clean shop towels.
   Torque spec

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

   Disconnect fuel rail and injectors
   Disconnect fuel supply line using fuel line disconnect tool. Disconnect all four fuel injector electrical connectors. Remove fuel rail mounting bolts. Carefully pull fuel rail with injectors straight up and out of intake manifold. Place fuel rail assembly aside on clean surface.
   ⚠Fuel injectors are fragile. Do not bend or apply side loads to injectors when removing fuel rail.
   Torque spec

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

   Disconnect coolant and PCV lines
   Locate coolant hoses connected to intake manifold (typically for EGR or coolant crossover). Place drain pan beneath connections. Loosen hose clamps and disconnect coolant hoses, draining residual coolant into pan. Remove PCV valve by rotating counterclockwise and pulling out.
   ⚠Some coolant will drain from hoses. Have drain pan and towels ready.
   Torque spec

   PCV Valve8 Nm (6 lb-ft)
5. 5

   Disconnect remaining sensors and harnesses
   Disconnect intake manifold absolute pressure (MAP) sensor electrical connector. Disconnect intake manifold tuning (IMT) valve connector if equipped. Remove any wiring harness brackets or clips attached to intake manifold. Label all connections for reassembly.
6. 6

   Remove intake manifold brackets and supports
   Locate and remove any support brackets connecting intake manifold to engine block or cylinder head. These are typically located at the rear of the manifold. Remove mounting bolts securing brackets.
   Torque spec

   Mounting Bolts45 Nm (33 lb-ft)
7. 7

   Remove intake manifold bolts
   Remove intake manifold mounting bolts in reverse order of tightening sequence (outside to center). There are typically 8-10 bolts securing the manifold. Keep bolts organized and note any differences in length or location.
   ℹ️Some bolts may be different lengths. Note positions during removal for correct reinstallation.
   Torque spec

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

   Remove intake manifold
   Carefully lift intake manifold off cylinder head. Manifold may be stuck due to gasket seal. Gently work manifold free if necessary, being careful not to damage mating surfaces. Remove and discard old intake manifold gasket.
   ⚠Do not pry between manifold and cylinder head as this will damage sealing surfaces.
9. 9

   Clean mating surfaces
   Thoroughly clean intake manifold and cylinder head mating surfaces. Remove all gasket material using plastic scraper (never metal). Use brake cleaner and shop towels to remove all oil and debris. Inspect surfaces for damage, warping, or cracks. Cover intake ports with clean towels to prevent debris from entering engine.
   ⚠️Do not allow any debris, bolts, or tools to fall into open intake ports. Foreign objects will cause catastrophic engine damage.
10. 10

    Install new gasket and position manifold
    Remove towels from intake ports. Position new intake manifold gasket on cylinder head, ensuring all ports and bolt holes align correctly. Carefully lower new or cleaned intake manifold onto gasket, aligning all bolt holes. Do not use any sealant unless specifically required by service manual.
11. 11

    Install and torque intake manifold bolts
    Hand-thread all intake manifold bolts finger-tight. Using torque wrench, tighten bolts to specification in proper sequence (center outward pattern). Verify with service manual for exact tightening sequence diagram. Make multiple passes, gradually increasing torque to final specification.
    ⚠Improper tightening sequence will cause gasket failure and vacuum leaks. Always follow center-outward pattern.
    Torque spec

    Intake Manifold Bolts25 Nm (18 lb-ft)
12. 12

    Reinstall brackets and supports
    Reinstall intake manifold support brackets and secure with mounting bolts torqued to specification. Ensure all brackets are properly seated before tightening.
    Torque spec

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

    Reinstall PCV valve and coolant lines
    Install new PCV valve O-ring/seal. Install PCV valve into intake manifold and torque to specification. Reconnect coolant hoses to intake manifold and secure with new hose clamps. Ensure hoses are fully seated on fittings.
    Torque spec

    PCV Valve8 Nm (6 lb-ft)
14. 14

    Reinstall fuel rail and injectors
    Inspect fuel injector O-rings and replace if damaged or disturbed. Lubricate O-rings with clean engine oil. Carefully position fuel rail with injectors over intake manifold ports. Press injectors straight down into ports until fully seated. Install fuel rail bolts and torque in proper sequence per service manual.
    ⚠Ensure injectors are fully seated before tightening fuel rail bolts. Partially seated injectors will cause fuel leaks.
    Torque spec

    Fuel Rail Bolts12 Nm (9 lb-ft)
15. 15

    Reinstall throttle body and connect all components
    Install new throttle body gasket. Position throttle body and install bolts, torquing to specification in cross pattern. Reconnect all electrical connectors (throttle body, injectors, MAP sensor, IMT valve). Reconnect all vacuum hoses per labels. Reconnect fuel supply line until it clicks. Reinstall air intake system and reconnect MAF sensor. Reinstall engine cover.
    Torque spec

    Throttle Body Bolts10 Nm (7 lb-ft)

Reassembly

1. Refill cooling system with Honda Type 2 Coolant to proper level
2. Reconnect negative battery terminal
3. Perform throttle body relearn procedure: Turn ignition ON (engine OFF) for 2 seconds, then OFF for 10 seconds. Repeat 3 times
4. Prime fuel system by cycling ignition ON for 2 seconds (without starting) 3-4 times

Verification

• Start engine and check for fuel leaks at fuel rail and supply line connections
• Check for coolant leaks at intake manifold coolant connections
• Check for vacuum leaks by listening for hissing sounds at intake manifold gasket
• Allow engine to reach operating temperature and verify smooth idle (no hunting or fluctuation)
• Check for diagnostic trouble codes (DTCs) using scan tool
• Verify throttle response is normal with no hesitation
• Recheck coolant level after engine cools and top off if necessary

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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