This procedure covers the removal and replacement of a single ignition coil on the 2014-2019 Toyota Corolla 1.8L I4 engine.

Warnings

Tools required

Parts

• Ignition coil × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and set parking brake
2. Turn ignition off and remove key
3. Allow engine to cool for at least 30 minutes if recently operated
4. Open hood and secure with prop rod

Procedure

1. 1

   Locate the faulty ignition coil
   The four ignition coils are located on top of the engine valve cover. Identify which cylinder requires coil replacement (cylinders numbered 1-4 from timing belt side to transmission side). Note the position for reinstallation.
2. 2

   Disconnect the coil electrical connector
   Press down on the locking tab of the electrical connector attached to the ignition coil and pull the connector straight up to disconnect. Do not pull on the wiring harness itself.
3. 3

   Remove the ignition coil mounting bolt
   Using a 10mm socket with extension, remove the single bolt securing the ignition coil to the valve cover. Keep the bolt in a safe location for reinstallation.
   Torque spec

   Ignition Coil Bolts8 Nm (6 lb-ft)
4. 4

   Extract the ignition coil
   Grasp the ignition coil firmly and pull straight up with steady pressure. The coil may require a slight twisting motion to break the seal. Once free, carefully lift the coil out of the spark plug well, ensuring no debris falls into the cylinder.
5. 5

   Inspect the spark plug well
   Visually inspect the spark plug well for oil, debris, or damage. If oil is present, this indicates a valve cover gasket leak that should be addressed. Use compressed air to clean any debris from the well if necessary, being careful not to blow debris into the engine.
6. 6

   Prepare the new ignition coil
   Remove the new ignition coil from packaging. Apply a thin coat of dielectric grease to the inside of the coil boot where it contacts the spark plug terminal. This prevents moisture intrusion and aids future removal.
7. 7

   Install the new ignition coil
   Carefully lower the new ignition coil into the spark plug well, ensuring the boot seats fully onto the spark plug terminal. Align the mounting hole with the threaded hole in the valve cover. Press down firmly to ensure complete seating.
8. 8

   Secure the ignition coil
   Install the ignition coil mounting bolt and tighten by hand until snug. Using a torque wrench, tighten the bolt to the specified torque of 8.0 Nm (6.0 lb-ft). Do not overtighten as this can crack the coil housing.
   Torque spec

   Ignition Coil Bolts8 Nm (6 lb-ft)
9. 9

   Reconnect the electrical connector
   Push the electrical connector onto the ignition coil until you hear and feel a distinct click, indicating the locking tab has engaged. Gently tug on the connector to verify it is fully seated and locked.

Reassembly

1. Ensure all electrical connectors are firmly seated and locked
2. Verify no tools or materials were left in the engine compartment
3. Close hood securely

Verification

• Start the engine and verify it runs smoothly without misfires or rough idle
• Check that the check engine light does not illuminate
• Listen for any unusual noises from the engine
• If replacing due to a misfire code, clear diagnostic trouble codes and test drive to confirm the issue is resolved

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