how to fix P0301 code on Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the engine is cool before starting work.

2. Replace Spark Plug

• Remove the engine cover if applicable.
• Use a socket wrench to remove the spark plug from cylinder 1.
• Check the gap on the new spark plug per manufacturer's specifications (usually around 0.043 inches for Toyota).
• Install the new spark plug, tightening it to the manufacturer's torque specification (typically around 13 lb-ft).
• Reconnect the ignition coil and engine cover.

3. Inspect and Replace Ignition Coil (if needed)

• Remove the ignition coil from cylinder 1 by unscrewing the mounting bolts.
• Visually inspect for cracks or damage.
• If faulty, install a new ignition coil, ensuring it is seated properly.
• Reconnect electrical connectors securely.

4. Check and Replace Fuel Injector (if necessary)

• Disconnect the fuel injector electrical connector.
• Remove the fuel rail if necessary to access the injector.
• Use an injector cleaning tool or replace the injector with a new one.
• Reassemble the fuel rail and reconnect all connections.

5. Perform Compression Test

• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine several times and record the compression reading.
• If compression is below the manufacturer’s specification (usually around 120 psi), further investigation is required.