Air Injection Check Valve

This procedure covers the removal and replacement of the air injection check valve on the 3.5L EcoBoost V6 engine, which prevents reverse flow in the secondary air injection system.

Warnings

Tools required

Parts

• Air injection check valve × 1 — Use OEM specification
• Air injection system gasket × 1 — Use OEM specification
• Hose clamps (if damaged) × 2 — Use OEM specification

Preparation

1. Ensure engine is completely cold to the touch
2. Disconnect negative battery cable and wait 2 minutes
3. Raise and support vehicle on jack stands if accessing from below (RWD configuration may require underside access)
4. Remove engine cover by pulling upward on clip fasteners
5. Locate air injection check valve on passenger side of engine near turbocharger assembly

Procedure

1. 1

   Access Air Injection Components
   Remove any heat shields or covers blocking access to the air injection check valve. The valve is typically located between the secondary air pump and the exhaust manifold on the passenger side. Remove heat shield bolts if present to gain clearance.
2. 2

   Disconnect Electrical Connector
   If the check valve has an electrical connector for monitoring purposes, press the release tab and disconnect it. Move the wiring harness aside and secure it away from hot components.
3. 3

   Disconnect Inlet Hose
   Loosen the hose clamp on the inlet side (from air pump) of the check valve using pliers or a screwdriver. Twist the hose gently to break any seal, then pull it off the check valve inlet. Inspect hose for cracks or deterioration.
4. 4

   Disconnect Outlet Connection
   The outlet side connects to the exhaust system. Depending on configuration, this may be a flanged connection with bolts or another clamped hose connection. For flanged connections, remove the mounting bolts. Apply penetrating oil if fasteners are corroded.
5. 5

   Remove Check Valve Mounting Hardware
   Remove the bolts or bracket securing the check valve body to the engine or chassis mounting point. Support the check valve while removing the final fastener to prevent it from falling.
6. 6

   Remove Check Valve Assembly
   Carefully maneuver the check valve out of the engine bay. Note the orientation of the valve (arrow indicating flow direction) and routing of any attached hoses for proper installation of the replacement.
7. 7

   Inspect Mating Surfaces
   Clean all mating surfaces where the check valve connects to other components. Remove old gasket material completely using a scraper, being careful not to damage sealing surfaces. Inspect exhaust connection points for damage or excessive corrosion.
8. 8

   Install New Check Valve
   Position the new check valve in the mounting location, ensuring the flow direction arrow points toward the exhaust manifold. Install new gasket on flanged connection if applicable. Hand-thread all mounting bolts before tightening any.
9. 9

   Secure Check Valve Mounting
   Torque the mounting bolts to specification in a criss-cross pattern if multiple bolts are present. Ensure the valve is properly seated and aligned before final tightening.
10. 10

    Connect Outlet to Exhaust System
    Apply anti-seize compound to exhaust flange bolt threads. Install new gasket if equipped. Connect the check valve outlet to the exhaust manifold port or pipe and torque fasteners to specification.
11. 11

    Connect Inlet Hose
    Slide the inlet hose from the air pump fully onto the check valve inlet fitting. Position the hose clamp over the connection point and tighten securely. Ensure hose is not kinked or touching hot surfaces.
12. 12

    Reconnect Electrical Components
    Reconnect any electrical connectors to the check valve, ensuring they click firmly into place. Route wiring away from hot exhaust components and moving parts.
13. 13

    Reinstall Heat Shields and Covers
    Reinstall any heat shields removed for access. Torque heat shield bolts to specification. Reinstall engine cover by pressing down on clip locations until seated.

Reassembly

1. Ensure all hose clamps are tight and hoses are properly routed away from heat sources
2. Verify all electrical connectors are fully seated and locked
3. Double-check that all mounting hardware is torqued to specification
4. Reconnect negative battery cable

Verification

• Start engine and listen for abnormal hissing or air leak sounds from the check valve area
• Allow engine to reach operating temperature and verify secondary air injection system operates normally (may hear air pump engage during cold start)
• Check for exhaust leaks around check valve connections using soapy water or leak detector spray
• Scan for diagnostic trouble codes using OBD-II scanner; clear any codes related to air injection system and verify they do not return
• Verify check engine light is not illuminated after completing 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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