This procedure covers the removal and replacement of the air injection check valve on a 2016-2024 Hyundai Tucson with the 2.5L I4 engine and AWD configuration.

Warnings

Tools required

Parts

• Air injection check valve × 1 — Use OEM specification
• Check valve gasket × 1 — Use OEM specification
• Exhaust flange gasket × 1 — Use OEM specification as needed

Preparation

1. Park vehicle on level ground and apply parking brake
2. Place wheel chocks behind rear wheels
3. Allow engine and exhaust system to cool completely (minimum 2 hours after operation)
4. Raise front of vehicle and secure on jack stands
5. Remove engine splash shield if equipped
6. Disconnect negative battery terminal to prevent accidental air pump activation
7. Apply penetrating oil to all exhaust connections and allow 15 minutes to soak

Procedure

1. 1

   Locate air injection check valve
   The check valve is located on the exhaust manifold on the passenger side of the engine bay. It connects the air injection pump line to the exhaust system. Identify the valve assembly and trace air supply lines from the air pump to confirm proper component identification.
2. 2

   Disconnect air supply line
   Disconnect the air supply hose from the air pump side of the check valve. Press the quick-connect fitting release tab and pull the line away from the valve. Cap or plug the air pump line to prevent debris entry.
3. 3

   Remove heat shield (if present)
   If a heat shield covers the check valve area, remove the retaining bolts using a 10mm socket. Set heat shield and hardware aside for reinstallation.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
4. 4

   Disconnect electrical connector
   If the check valve has an integrated pressure sensor or electrical connection, press the locking tab and disconnect the electrical connector. Move wiring harness aside to provide clearance.
5. 5

   Remove check valve mounting bolts
   Remove the bolts securing the check valve to the exhaust manifold or pipe using the appropriate socket (typically 12mm or 14mm). Support the valve assembly as you remove the final bolt to prevent it from falling.
   ⚠If bolts are severely corroded or stuck, apply additional penetrating oil and use a breaker bar. Do not force to avoid breaking exhaust studs.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
6. 6

   Remove check valve from exhaust
   Carefully separate the check valve from the exhaust manifold or pipe. Remove and discard the old gasket. If the valve is stuck due to carbon buildup, gently twist while pulling to break the seal.
7. 7

   Clean mating surfaces
   Use a wire brush or gasket scraper to thoroughly clean the exhaust manifold mating surface where the check valve connects. Remove all carbon deposits, old gasket material, and rust. Vacuum away debris to prevent it from entering the exhaust system.
   ⚠Do not gouge or scratch the mating surface as this will prevent proper sealing and may cause exhaust leaks.
8. 8

   Inspect exhaust threads and studs
   Examine the threaded mounting holes or studs on the exhaust manifold. Clean threads with a wire brush. If studs are damaged or threads are stripped, repair must be completed before proceeding.
9. 9

   Install new check valve
   Position the new gasket on the exhaust manifold mating surface. Apply a thin coat of anti-seize to the mounting bolt threads (not the gasket surface). Position the new check valve and hand-thread all mounting bolts to ensure proper alignment before tightening.
   ℹ️Ensure the check valve is oriented correctly with the flow direction arrow pointing toward the exhaust manifold, away from the air pump.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
10. 10

    Torque mounting bolts
    Using a torque wrench, tighten the check valve mounting bolts in a cross-pattern to the specified torque. This ensures even gasket compression and proper sealing.
    Torque spec

    Mounting Bolts27 Nm (20 lb-ft)
11. 11

    Reconnect air supply line
    Connect the air supply hose to the check valve inlet. Push the quick-connect fitting firmly until you hear or feel it click into place. Gently tug on the line to verify it is properly secured.
12. 12

    Reconnect electrical connector
    If applicable, reconnect the electrical connector to the check valve or pressure sensor. Ensure the connector locks securely in place.
13. 13

    Reinstall heat shield
    If a heat shield was removed, position it back in place and install the retaining bolts. Torque to specification.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

Reassembly

1. Reinstall engine splash shield if removed
2. Reconnect negative battery terminal
3. Lower vehicle from jack stands
4. Remove wheel chocks

Verification

• Start engine and allow to idle. Listen for any exhaust leaks at the check valve connection. A hissing sound indicates improper sealing.
• With engine running, verify no abnormal air pump noise or pressure-related fault codes.
• Perform a cold start test cycle to verify the air injection system activates properly and the check valve prevents backflow.
• Use a scan tool to check for air injection system fault codes. Clear any pre-existing codes and verify none return after test drive.
• Inspect the check valve area for any signs of exhaust leaks after the engine reaches operating temperature.

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