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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety while working on the engine.
• Allow the engine to cool completely before starting work.

2. Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector from cylinder 1.
• Unbolt the ignition coil and remove it.
• Use the spark plug socket to remove the spark plug from cylinder 1.
• Inspect the old spark plug for wear; replace it with a new one, ensuring the gap is set according to manufacturer specifications (typically 0.044 inches).
• Torque the new spark plug to the manufacturer's specification (usually around 13-15 lb-ft).
• Reinstall the ignition coil, securing it with bolts and re-connecting the electrical connector.

3. Replace Ignition Coil (if necessary)

• If the ignition coil tested faulty, replace it with a new one.
• Disconnect the ignition coil connector.
• Unbolt and remove the faulty ignition coil.
• Install the new ignition coil, ensuring it is seated properly.
• Reconnect the ignition coil connector.

4. Check/Replace Fuel Injector (if necessary)

• If the fuel injector is suspected to be clogged, remove it by disconnecting the fuel line and electrical connector.
• Use a fuel injector cleaning kit or replace the injector if cleaning is insufficient.
• Reinstall the fuel injector, ensuring it is properly seated and the fuel line is securely connected.

5. Final Assembly

• Reinstall any components that were removed, such as the engine cover.
• Reconnect the negative battery terminal.