how to fix the P0301 misfire code in my Toyota Highlander XU70 (2020-Present)?

Solution

1. Preparation

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

2. Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench.
• Remove the ignition coil from cylinder 1 by unscrewing the bolts and carefully pulling it out.
• Remove the old spark plug using the spark plug socket.
• Inspect the spark plug gap and replace it with a new spark plug, ensuring it is properly gapped to manufacturer specifications (typically 0.043 inches for Toyota).
• Torque the spark plug to the recommended value (usually around 13 lb-ft).
• Reinstall the ignition coil and secure it with the bolts.

3. Inspect and Replace Ignition Coil

• Tools Required: Multimeter, socket set.
• If the ignition coil appears faulty, remove it from cylinder 1.
• Check the primary and secondary resistance using the multimeter; consult the service manual for specific resistance values.
• If outside the specified range, replace the ignition coil with a new one.
• Reinstall the ignition coil and ensure it is seated properly.

4. Inspect and Clean Fuel Injector

• Tools Required: Fuel injector cleaner, fuel line disconnect tool.
• Disconnect the fuel line from the injector and remove the injector from cylinder 1.
• Clean the injector using a fuel injector cleaning solution or replace it if it's found to be clogged or malfunctioning.
• Reinstall the cleaned or new injector, ensuring it is secured properly and reconnect the fuel line.

5. Perform Compression Test

• Tools Required: Compression gauge.
• Remove the spark plug from cylinder 1 and install the compression gauge.
• Crank the engine and record the compression reading; compare it to manufacturer specifications.
• If compression is low, further inspection of valves and piston rings may be necessary.