how to fix P0301 code in Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather all tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench, anti-seize compound.
• Sub-steps:
  1. Remove the ignition coil by unscrewing it from the cylinder head.
  2. Disconnect the electrical connector from the ignition coil.
  3. Use the spark plug socket to remove the old spark plug.
  4. Apply a small amount of anti-seize compound to the threads of the new spark plug.
  5. Install the new spark plug and torque it to the manufacturer’s specification (typically around 13-16 lb-ft).
  6. Reconnect the ignition coil and secure it in place.

3. Inspect and Replace Ignition Coil

• Tools Required: Screwdrivers, ratchet set.
• Sub-steps:
  1. If the spark plug replacement did not resolve the issue, remove the ignition coil from cylinder 1.
  2. Inspect the coil for cracks or damage.
  3. Test the ignition coil using a multimeter to ensure it is functioning correctly.
  4. If faulty, replace the ignition coil with a new one.
  5. Reinstall the ignition coil and reconnect the electrical connector.

4. Check Fuel Injector

• Tools Required: Fuel injector cleaning kit or multimeter (for testing).
• Sub-steps:
  1. Disconnect the fuel injector connector for cylinder 1.
  2. Use a multimeter to check the resistance of the injector; it should be within the specified range (consult manufacturer specifications).
  3. If the injector is faulty, remove it and replace it with a new one.
  4. Reconnect the fuel injector connector after replacement.

5. Conduct Compression Test

• Tools Required: Compression tester.
• Sub-steps:
  1. Remove the spark plug from cylinder 1.
  2. Insert the compression tester into the spark plug hole.
  3. Crank the engine for a few seconds and record the compression reading.
  4. If the compression is lower than specified (consult manufacturer specs), further engine diagnosis may be required.