This procedure covers the removal and replacement of the knock sensor(s) on the 2021-2024 Ford F-150 3.5L V6 EcoBoost engine, requiring removal of the intake manifold for access.

Warnings

Tools required

Parts

• Knock sensor × 2 — Motorcraft DY-1316 or equivalent
• Intake manifold gaskets × 1 — Use OEM specification
• Fuel rail O-rings × 1 — Use OEM specification

Fluids

• Motorcraft 0W-20 Full Synthetic — 0.5 qt

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery cable and wait 2 minutes for systems to power down
4. Remove engine cover by pulling upward on front clips
5. Relieve fuel system pressure by removing fuel pump fuse and cranking engine until it stalls
6. Place oil drain pan beneath engine to catch any coolant or oil spillage

Procedure

1. 1

   Disconnect air intake system
   Loosen clamp at throttle body and disconnect air intake tube. Disconnect mass airflow sensor electrical connector. Remove entire air intake assembly from vehicle to provide working room.
2. 2

   Disconnect fuel system components
   Disconnect fuel line quick-connect fittings at fuel rail by pressing release tabs. Disconnect fuel injector electrical connectors by releasing red locking tabs and pulling connectors straight off. Label connectors if needed for reassembly reference.
   ⚠Have shop towels ready to catch residual fuel from fuel rail. Dispose of fuel-soaked towels properly.
3. 3

   Remove accessory connections
   Disconnect throttle body electrical connector. Disconnect PCV hoses from valve covers. Disconnect vacuum lines from intake manifold, marking their positions for reassembly. Disconnect brake booster vacuum line if it interferes with manifold removal.
4. 4

   Remove intake manifold mounting bolts
   Remove all intake manifold mounting bolts in reverse order of tightening sequence (work from outside toward center). There are typically 10 bolts securing the intake manifold. Keep bolts organized by location as some may be different lengths.
5. 5

   Remove intake manifold
   Carefully lift intake manifold assembly upward and away from engine. It may require gentle rocking to break gasket seal. Be careful not to damage fuel injector tips. Once free, cover open intake ports with clean shop towels to prevent debris entry.
   ⚠Manifold is heavy and awkward. Use assistant or support device to prevent dropping.
6. 6

   Locate and access knock sensors
   Identify the two knock sensors in the engine valley between cylinder banks. They are cylindrical sensors with single-wire electrical connectors. Disconnect both knock sensor electrical connectors by pressing release tab and pulling straight up.
   ℹ️Take note of sensor positions - left bank and right bank sensors may have different part numbers or orientations.
7. 7

   Remove knock sensors
   Using appropriate socket (typically 22mm), carefully remove both knock sensors by turning counterclockwise. Avoid using excessive force. If sensors are seized, apply penetrating oil and allow to soak before removal attempt.
   ⚠Do not pry on sensors or damage mounting bosses in engine block.
8. 8

   Clean sensor mounting surfaces
   Thoroughly clean knock sensor mounting holes in engine block using parts cleaning solvent and shop towels. Remove any old anti-seize compound, carbon deposits, or corrosion. Ensure mounting surfaces are completely clean and dry for proper sensor contact.
9. 9

   Install new knock sensors
   Hand-thread new knock sensors into mounting holes, ensuring they thread smoothly without cross-threading. Tighten knock sensors to proper specification using torque wrench. Proper torque is critical for correct sensor operation and signal quality.
   ⚠Do not apply anti-seize or thread sealant unless specifically required by manufacturer. This can affect sensor grounding and cause false readings.
   Torque spec

   Knock Sensor20 Nm (15 lb-ft)
10. 10

    Reconnect knock sensor connectors
    Connect electrical connectors to both knock sensors, ensuring they click securely into place. Verify connectors are fully seated and locking tabs engage properly. Route wiring harness to avoid pinch points during manifold installation.
11. 11

    Clean intake manifold mating surfaces
    Using plastic scraper and cleaning solvent, remove all old gasket material from intake manifold and cylinder head mating surfaces. Surfaces must be completely clean and free of debris. Use compressed air or vacuum to remove loose particles from intake ports.
12. 12

    Install new intake manifold gaskets
    Position new intake manifold gaskets on cylinder heads, ensuring all alignment pins engage properly. Verify gaskets are correctly oriented and fuel injector O-rings are in good condition or replaced. Do not reuse old gaskets.
13. 13

    Reinstall intake manifold
    Remove protective towels from intake ports. Carefully lower intake manifold onto engine, guiding fuel injectors into their bores. Ensure manifold seats evenly on gaskets. Hand-thread all mounting bolts before tightening any.
    Torque spec

    Mounting Bolts54 Nm (40 lb-ft)
14. 14

    Reconnect all systems
    Reconnect all vacuum lines, PCV hoses, throttle body connector, fuel injector connectors, and fuel lines. Ensure all quick-connect fittings click securely. Reinstall air intake system and reconnect mass airflow sensor. Reconnect negative battery cable.

Reassembly

1. Tighten intake manifold bolts in proper sequence from center outward in multiple passes to final torque specification
2. Double-check that all electrical connectors are fully seated with locking tabs engaged
3. Verify all vacuum lines and hoses are properly connected and secured
4. Reinstall engine cover by pressing down firmly on mounting clips

Verification

• Turn ignition to ON position without starting engine and listen for fuel pump priming (2-3 seconds)
• Check for fuel leaks around fuel rail and connections
• Start engine and verify it idles smoothly without rough running or knocking sounds
• Check for vacuum leaks by listening for hissing sounds around intake manifold
• Use scan tool to verify no knock sensor diagnostic trouble codes are present
• Perform test drive and verify normal engine performance without detonation or reduced power
• Monitor knock sensor values with scan tool during test drive to confirm proper operation
• Recheck all connections and fasteners after test drive

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