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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shocks and short circuits.
• Allow the engine to cool before starting work.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 1:
  • Use a socket set to remove the coil mounting bolts.
  • Carefully pull the coil straight up to avoid damaging the connector.
• Remove the spark plug:
  • Use a spark plug socket to unscrew the spark plug.
  • Inspect the spark plug for signs of wear, carbon buildup, or damage.
• Replace the spark plug:
  • Install a new spark plug (ensure it is the correct type as per the manufacturer’s specifications).
  • Torque the spark plug to the manufacturer’s specification (typically around 13-16 lb-ft).

3. Inspect and Replace Ignition Coil

• If the spark plug is in good condition, inspect the ignition coil:
  • Test the ignition coil using a multimeter for resistance (compare with specifications).
• Replace the ignition coil if defective:
  • Install the new ignition coil onto the spark plug.
  • Secure it with the mounting bolts and reconnect the electrical connector.

4. Check and Repair Fuel Injector

• Inspect the fuel injector for cylinder 1:
  • Disconnect the fuel injector connector.
  • Perform a resistance test to ensure it is within specifications.
• Replace the fuel injector if defective:
  • Remove the fuel rail if necessary to access the injector.
  • Replace with a new injector and ensure it is properly seated.
  • Reconnect the fuel injector connector.

5. Reassemble and Reconnect Battery

• Reinstall any components that were removed during the inspection and repair process.
• Reconnect the negative battery terminal securely.