how to fix my Toyota Highlander Third Generation (2014-2019) with a P0301 code

Solution

1. Preparation

• Gather all necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench.
• Remove the ignition coil for cylinder 1 by unscrewing the mounting bolts and disconnecting the electrical connector.
• Remove the spark plug using the spark plug socket and ratchet.
• Inspect the spark plug for signs of wear or damage; replace with a new spark plug if necessary (ensure correct gap settings).
• Reinstall the spark plug and torque it to the manufacturer's specifications (typically around 13 lb-ft).
• Reattach the ignition coil and ensure the connector is properly secured.

3. Inspect and Replace Ignition Coil (if necessary)

• If the spark plug is in good condition, test the ignition coil using a multimeter.
• If the coil is faulty, remove it and replace with a new ignition coil.
• Reinstall the ignition coil and secure it with bolts.

4. Check Fuel Injector Operation

• Disconnect the fuel injector connector for cylinder 1.
• Use a multimeter to test the injector for resistance; if it's out of specs, replace the injector.
• Reconnect the fuel injector connector after confirming it’s functioning.

5. Address Any Vacuum Leaks

• Inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
• Replace any damaged hoses and ensure all connections are tight.

6. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0301 code from the ECU.