This procedure covers the removal and replacement of the Idle Air Control (IAC) valve on the 2014-2019 Toyota Corolla 1.8L I4 engine to address idle speed irregularities or stalling issues.

Warnings

Tools required

Parts

• Idle Air Control Valve × 1 — 22270-0T020 or equivalent
• IAC valve gasket or O-ring × 1 — Use OEM specification
• Throttle body gasket (if damaged) × 1 — Use OEM specification

Fluids

• Toyota Super Long Life Coolant (Pink) — 0.5 qt

Preparation

1. Ensure engine is completely cool to the touch
2. Disconnect negative battery terminal and wait 3 minutes for system discharge
3. Place drain pan under throttle body area to catch any coolant drips
4. Remove engine cover by pulling upward on front clips and lifting off
5. Locate the IAC valve on the side of the throttle body assembly

Procedure

1. 1

   Disconnect IAC valve electrical connector
   Press the locking tab on the IAC valve electrical connector and pull straight away from the valve. Do not pull on the wires themselves. If connector is stuck, gently wiggle while pulling.
2. 2

   Disconnect coolant bypass hoses (if equipped)
   Using pliers, slide the hose clamps away from the IAC valve connections. Note the orientation of both hoses before removal. Gently twist and pull the coolant hoses off the IAC valve ports. Allow residual coolant to drain into the pan. Plug hose ends with clean rags to minimize coolant loss.
   ⚠Even on a cold engine, some warm coolant may drain from these hoses.
3. 3

   Remove IAC valve mounting screws
   Using a Phillips screwdriver or appropriate socket, remove the two IAC valve mounting screws. Keep these screws in a safe place as they are small and easily lost. Support the valve with your other hand to prevent it from falling when the last screw is removed.
4. 4

   Remove IAC valve from throttle body
   Gently pull the IAC valve straight out from the throttle body. If it resists, carefully wiggle it side to side while pulling. Do not pry against the throttle body mounting surface as this will cause damage. Remove and discard the old gasket or O-ring from the valve or throttle body.
5. 5

   Clean mounting surface
   Using throttle body cleaner and a clean shop towel, thoroughly clean the IAC valve mounting surface on the throttle body. Remove all traces of old gasket material, carbon deposits, and debris. Ensure the air passages are clean and unobstructed. Inspect the bore for damage or excessive wear.
6. 6

   Inspect and prepare new IAC valve
   Verify the new IAC valve matches the old unit exactly in connector type and mounting configuration. Install the new gasket or O-ring onto the new IAC valve, ensuring it seats properly in its groove. Do not use sealant unless specifically required by the manufacturer.
7. 7

   Install new IAC valve
   Carefully align the new IAC valve with the throttle body bore, ensuring the gasket remains properly positioned. The valve should slide in smoothly without force. Align the mounting screw holes and ensure the valve is fully seated against the throttle body mounting surface.
8. 8

   Install and torque mounting screws
   Hand-thread both IAC valve screws to prevent cross-threading. Tighten screws in a crossing pattern (alternating between screws) to ensure even gasket compression. Using a torque wrench, tighten both screws to specification. Do not overtighten as this can strip the aluminum threads in the throttle body.
   ⚠These screws thread into aluminum and are very easy to strip. Use proper torque and technique.
   Torque spec

   IAC Valve Screws3 Nm (2 lb-ft)
9. 9

   Reconnect coolant hoses (if equipped)
   Slide the coolant hoses back onto the IAC valve ports in their original orientation. Ensure hoses are pushed fully onto the ports. Reposition the hose clamps over the connection points and verify they are secure.
10. 10

    Reconnect electrical connector
    Push the electrical connector onto the IAC valve until it clicks into place. Verify the locking tab is fully engaged by gently pulling on the connector body (not the wires).
11. 11

    Reinstall engine cover and reconnect battery
    Replace the engine cover by aligning the clips and pressing down until fully seated. Reconnect the negative battery terminal. Check coolant level in the reservoir and add Toyota Super Long Life Coolant as needed to bring level to the FULL mark.

Reassembly

1. Ensure all electrical connections are secure and properly locked
2. Verify all coolant hoses are properly connected with clamps in place
3. Double-check that no tools or shop towels were left in the engine bay

Verification

• Start the engine and allow it to warm up to operating temperature while monitoring for coolant leaks around the IAC valve
• Verify idle speed is smooth and steady between 600-800 RPM when fully warmed up
• With engine at operating temperature, turn on accessories (A/C, headlights, rear defrost) and verify idle compensates appropriately without stalling
• Check for diagnostic trouble codes using an OBD-II scanner - no IAC-related codes should be present
• Test drive the vehicle and verify no stalling occurs during deceleration or when coming to stops
• Recheck coolant level after test drive and top off if necessary

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