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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil from cylinder 1 by unscrewing the retaining bolts and lifting it off.
• Use a spark plug socket to remove the spark plug from cylinder 1.
• Inspect the spark plug for wear, carbon buildup, or damage. Replace if necessary.
• Install the new spark plug and torque to manufacturer specifications (typically around 13 ft-lbs).
• Reinstall the ignition coil securely.

3. Check and Replace Ignition Coil

• Tools Required: Socket set, multimeter.
• Test the ignition coil's primary and secondary resistance with a multimeter.
• If the readings are outside the manufacturer's specifications, replace the ignition coil for cylinder 1.
• Reinstall the new ignition coil and ensure all connections are secure.

4. Inspect and Clean Fuel Injector

• Tools Required: Fuel injector cleaning kit (if cleaning), socket set.
• Remove the fuel injector from cylinder 1 by disconnecting the electrical connector and unscrewing the retaining bolts.
• Inspect the injector for blockage or damage. Clean it using a fuel injector cleaning kit if necessary, or replace with a new injector.
• Reinstall the fuel injector and reconnect the electrical connector.

5. Compression Test (if necessary)

• Tools Required: Compression gauge.
• Remove spark plugs from all cylinders.
• Insert the compression gauge into the spark plug hole of cylinder 1.
• Crank the engine for a few seconds and record the compression reading.
• Compare to manufacturer specifications; if low, further investigation into potential causes (valve issues, gasket leaks) is required.