how to troubleshoot the P0301 misfire code on my Toyota Highlander Fourth Generation (2020-present)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on ignition components.

2. Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench
• Remove the engine cover (if equipped) to access the spark plug.
• Use the spark plug socket to remove the spark plug from cylinder 1.
• Inspect the spark plug for signs of wear or damage (e.g., fouling, excessive wear).
• Install the new spark plug, torquing it to the manufacturer’s specifications (typically around 13 lb-ft).
• Reattach the engine cover.

3. Inspect and Replace Ignition Coil (if needed)

• Tools Required: Socket set, multimeter
• Disconnect the electrical connector from the ignition coil on cylinder 1.
• Remove the ignition coil from the cylinder head.
• Test the ignition coil with a multimeter to ensure it is within specifications (refer to the vehicle's service manual).
• If faulty, replace the ignition coil with a new one and reinstall it.

4. Test Fuel Injector

• Tools Required: Fuel injector tester
• Disconnect the fuel injector connector for cylinder 1.
• Use a fuel injector tester to check if the injector is receiving electrical signals and delivering fuel.
• If the injector is faulty, replace it with a new component.

5. Compression Test

• Tools Required: Compression tester
• Remove the spark plug from cylinder 1.
• Insert the compression tester and crank the engine to obtain a reading.
• Compare the reading with manufacturer specifications; if low, further investigation of the engine’s internals may be necessary.