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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative terminal of the battery.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector.
• Remove the ignition coil from cylinder 1 by unscrewing it.
• Remove the spark plug using a spark plug socket.
• Inspect the old spark plug for wear or damage. Replace if necessary.
• Install the new spark plug and torque it to manufacturer specifications (typically around 13 ft-lbs).
• Reinstall the ignition coil and reconnect the connector.

3. Check and Replace Ignition Coil

• If the spark plug is in good condition, inspect the ignition coil.
• Tools Required: Socket set, torque wrench.
• Remove the ignition coil from cylinder 1 as described above.
• Test the ignition coil with a multimeter for resistance; replace if readings are outside the specifications.
• Install the new ignition coil, ensuring it is seated properly and reconnect the wire harness.

4. Fuel Injector Inspection and Cleaning

• Tools Required: Fuel injector cleaner kit, basic hand tools.
• If misfire persists, remove the fuel injector from cylinder 1.
• Inspect the injector for clogs or damage. Clean it using a fuel injector cleaning kit or replace if necessary.
• Reinstall the fuel injector and ensure connections are secure.

5. Conduct Compression Test

• Tools Required: Compression tester.
• Ensure all spark plugs are removed for accurate readings.
• Insert compression tester into cylinder 1’s spark plug hole and crank the engine.
• Check the compression readings; they should be within the manufacturer's specifications (usually around 140-180 psi).
• If low, further engine diagnostics may be needed (valve issues, head gasket).