how to fix the P0301 misfire code on Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.
• Allow the engine to cool before opening any components.

2. Replace Spark Plug

• Remove the ignition coil from cylinder 1 by unscrewing the retaining bolts.
• Pull the ignition coil straight up to avoid damaging it.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear; replace with a new spark plug if necessary (gapping to manufacturer's specification).
• Reinstall the new spark plug and torque to manufacturer’s specification.

3. Replace Ignition Coil (if necessary)

• If the ignition coil shows signs of damage, replace it by:
  • Disconnecting the electrical connector.
  • Unscrewing the bolts securing the ignition coil.
  • Installing the new ignition coil and securing it with bolts.
  • Reconnecting the electrical connector.

4. Inspect and Clean Fuel Injector

• Remove the fuel rail assembly if necessary to access the fuel injector for cylinder 1.
• Disconnect the fuel line and the electrical connector from the injector.
• Remove the injector and inspect it for clogs.
• Clean the injector with a suitable cleaning solution or replace it if damaged.

5. Perform Compression Test

• Use a compression gauge to check the pressure in cylinder 1.
• If compression is below the manufacturer’s specifications, further engine diagnostics may be needed.

6. Reconnect Components

• Reinstall any components removed during the repair.
• Reconnect the battery and ensure all connections are secure.