Removal and replacement of the air injection check valve, which prevents exhaust gases from flowing back into the secondary air injection system.

Warnings

Tools required

Parts

• Air injection check valve × 1 — Use OEM specification
• Check valve gasket × 1 — Use OEM specification
• Air injection pipe gasket (if equipped) × 1 — Use OEM specification

Preparation

1. Ensure engine and exhaust system are completely cold (allow at least 2 hours after operation).
2. Park vehicle on level surface and engage parking brake.
3. Open hood and secure with prop rod.
4. If necessary for access, raise and support front of vehicle on jack stands.
5. Spray penetrating oil on check valve mounting bolts and allow to soak.

Procedure

1. 1

   Remove engine cover if equipped
   Remove plastic engine cover by pulling upward on the cover to release from mounting grommets. If secured with screws, remove cover screws using appropriate socket.
   Torque spec

   Cover Screws10 Nm (8 lb-ft)
2. 2

   Locate air injection check valve
   The check valve is typically located on or near the exhaust manifold, connected to the secondary air injection pipe. Trace the air injection hose from the air pump to locate the check valve assembly. It will be positioned between the air pump and the exhaust manifold.
   ℹ️On the 1.8L engine, the check valve is usually mounted on the passenger side of the engine compartment near the exhaust manifold.
3. 3

   Disconnect air injection hose
   Disconnect the air injection hose from the inlet side of the check valve. If equipped with a clamp, loosen the hose clamp and carefully twist and pull the hose from the check valve. Note the orientation and routing of the hose for reinstallation.
4. 4

   Remove heat shield if present
   If the check valve is protected by a heat shield, remove the heat shield mounting bolts and set the shield aside. Clean any corrosion from bolt threads with a wire brush.
   Torque spec

   Heat Shield Bolts10 Nm (7 lb-ft)
5. 5

   Disconnect check valve from exhaust manifold
   Remove the flange bolts connecting the check valve outlet to the exhaust manifold or injection pipe. Support the check valve assembly while removing the final bolt to prevent it from falling. Inspect the condition of the gasket and replace if damaged or compressed.
   ⚠Bolts may be difficult to remove due to heat cycling and corrosion. Apply additional penetrating oil and allow to soak if bolts resist turning.
   Torque spec

   Exhaust Flange Bolts45 Nm (33 lb-ft)
6. 6

   Remove check valve mounting bolts
   Remove any mounting bolts securing the check valve bracket to the engine block or cylinder head. Carefully remove the check valve assembly from the vehicle. Keep track of any spacers, washers, or brackets for reinstallation.
   Torque spec

   Mounting Bolts26 Nm (19 lb-ft)
7. 7

   Clean mounting surfaces
   Use a wire brush or gasket scraper to thoroughly clean all gasket mating surfaces on the exhaust manifold and air injection pipe. Remove all traces of old gasket material, carbon deposits, and corrosion. Wipe surfaces clean with a lint-free cloth.
8. 8

   Install new check valve gaskets
   Position new gaskets on the check valve inlet and outlet flanges. Ensure gaskets are properly aligned with bolt holes and are seated correctly in any locating grooves or tabs.
9. 9

   Position new check valve
   Install the new check valve in position, ensuring proper orientation. The arrow on the check valve body must point in the direction of airflow (from air pump toward exhaust manifold). Install mounting bolts finger-tight to hold assembly in position.
   ⚠Installing the check valve backward will prevent the secondary air injection system from functioning and may cause exhaust gases to damage the air pump.
10. 10

    Torque mounting bolts
    Apply anti-seize compound to mounting bolt threads. Torque the check valve mounting bolts to specification in a cross-pattern sequence to ensure even clamping force.
    Torque spec

    Mounting Bolts26 Nm (19 lb-ft)
11. 11

    Connect to exhaust manifold
    Apply anti-seize compound to flange bolt threads. Install and torque the flange bolts connecting the check valve outlet to the exhaust manifold or injection pipe in a cross-pattern sequence.
    Torque spec

    Exhaust Flange Bolts45 Nm (33 lb-ft)
12. 12

    Reinstall heat shield
    If a heat shield was removed, reinstall it and torque mounting bolts to specification. Ensure the heat shield does not contact any hoses or wiring.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)
13. 13

    Reconnect air injection hose
    Reconnect the air injection hose to the check valve inlet. Ensure the hose is fully seated on the check valve fitting. Tighten the hose clamp securely, positioning the clamp clear of any moving components or heat sources.
14. 14

    Reinstall engine cover
    Reinstall the engine cover by aligning with mounting grommets and pressing down firmly until seated. If equipped with cover screws, torque to specification.
    Torque spec

    Cover Screws10 Nm (8 lb-ft)

Reassembly

1. Double-check all fastener torque values and verify no tools or parts were left in engine compartment.
2. Ensure all hoses and electrical connections are properly secured and routed away from heat sources.
3. Lower vehicle from jack stands if raised.

Verification

• Start the engine and allow it to reach operating temperature while monitoring for exhaust leaks at the check valve connections.
• Listen for abnormal hissing or popping sounds from the check valve area that would indicate a leak or improper installation.
• Use an OBD-II scanner to verify no secondary air injection system fault codes are present.
• During cold start, verify the secondary air injection system activates (you should hear the air pump running for approximately 60-120 seconds).
• After test drive, visually inspect check valve and connections for any signs of exhaust leaks or loose components.

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