Air Injection Check Valve

This procedure covers the removal and replacement of the air injection check valve on the 2015-2020 Ford F-150 5.0L V8 Coyote engine, which prevents backflow in the secondary air injection system.

Warnings

Tools required

Parts

• Air injection check valve × 1 — Use OEM specification
• Air injection pipe gaskets × 2 — Use OEM specification

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level ground and engage parking brake
3. Disconnect negative battery cable and wait 5 minutes for system capacitors to discharge
4. Raise and support front of vehicle on jack stands if accessing from below
5. Apply penetrating oil to check valve mounting bolts and exhaust connections, let soak 10-15 minutes

Procedure

1. 1

   Remove engine cover
   Pull up on the engine cover to release the retaining grommets. Lift the cover away from the engine bay and set aside.
2. 2

   Disconnect air injection electrical connector
   Locate the air injection pump electrical connector near the front of the engine on the driver side. Press the release tab and disconnect the connector. Move the wiring harness aside for access.
3. 3

   Remove heat shield
   Remove the heat shield bolts covering the air injection check valve using a 10mm socket. There are typically 2-3 bolts securing the shield. Carefully remove the heat shield and set aside.
4. 4

   Disconnect air injection inlet hose
   Loosen the hose clamp on the inlet side of the check valve using a flathead screwdriver or 8mm socket. Twist and pull the hose free from the check valve. Note the orientation for reinstallation.
5. 5

   Disconnect air injection outlet pipe
   Remove the mounting bolts securing the outlet pipe to the check valve using a 13mm socket. There are typically two bolts at this connection. Separate the pipe from the check valve and note the condition of the gasket.
   ℹ️The outlet pipe may be stuck due to carbon buildup. Gently wiggle the connection while pulling to break it free.
6. 6

   Remove check valve mounting bracket
   Remove the mounting bolts securing the check valve bracket to the engine using a 13mm or 15mm socket depending on configuration. Support the check valve assembly as you remove the final bolt.
7. 7

   Remove check valve assembly
   Carefully maneuver the check valve assembly out of the engine bay. Watch for any remaining wiring or hose connections that may restrict removal. Inspect the old check valve for signs of failure such as rattling, carbon buildup, or damaged sealing surfaces.
8. 8

   Clean mating surfaces
   Use a plastic scraper to clean all gasket material and carbon deposits from the mounting surfaces on the outlet pipe connection and mounting bracket. Ensure all surfaces are clean and free of debris before installing the new check valve.
   ⚠Do not use metal scrapers on aluminum surfaces as they can cause damage that leads to vacuum leaks.
9. 9

   Install new check valve
   Position the new check valve into the mounting location. Ensure the arrow on the valve body points in the correct flow direction (from pump toward exhaust manifolds). Start all mounting bolts by hand before tightening to ensure proper alignment.
10. 10

    Connect outlet pipe with new gasket
    Install a new gasket on the outlet pipe connection. Position the outlet pipe to the check valve and install the mounting bolts. Apply anti-seize to the bolt threads. Torque the mounting bolts in a cross pattern to specification.
11. 11

    Reconnect inlet hose and electrical connector
    Slide the inlet hose onto the check valve inlet port and secure with the hose clamp. Ensure the hose is fully seated. Reconnect the air injection pump electrical connector until it clicks into place.
12. 12

    Reinstall heat shield and engine cover
    Position the heat shield over the check valve and install the mounting bolts. Torque to specification. Reinstall the engine cover by aligning the grommets and pressing down firmly until seated.

Reassembly

1. Reconnect the negative battery cable
2. Double-check all connections are secure and no tools were left in the engine bay
3. Lower vehicle from jack stands if raised

Verification

• Start the engine and listen for any abnormal hissing or air leak sounds from the check valve area
• Allow engine to reach operating temperature and verify no Check Engine Light appears
• Use a scan tool to check for air injection system codes (P0410, P0411, P0412)
• With engine at operating temperature, verify air injection pump operates during cold start simulation if equipped with appropriate scan tool
• Perform a visual inspection under the vehicle for any signs of exhaust leaks around the check valve connections

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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