how to fix P0301 misfire code in Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery negative terminal to prevent electrical shorts.
• Allow the engine to cool completely.

2. Replace Spark Plug and Ignition Coil

• Tools Required: Socket set, torque wrench, dielectric grease.
• Remove the engine cover if applicable.
• Disconnect the ignition coil connector and the mounting bolts.
• Pull the ignition coil out and inspect it for damage.
• Replace the spark plug in cylinder 1, ensuring it is gapped correctly (typically 0.043 inches for this model).
• Install the new ignition coil onto the spark plug and secure it with bolts. Reconnect the electrical connector.
• Apply dielectric grease to the connector to prevent moisture ingress.

3. Inspect and Clean Fuel Injector

• Tools Required: Fuel injector cleaning kit (if cleaning is needed).
• Disconnect the fuel injector connector.
• Remove the fuel rail if necessary to access the injector.
• Inspect the fuel injector for clogs or damage. Clean using a fuel injector cleaning kit if needed or replace it if damaged.
• Reassemble the fuel rail and reconnect the injector.

4. Check Engine Compression

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole and crank the engine a few times.
• Record the compression reading and compare it to specifications (typically around 180 psi).
• If the compression is low, further investigation (e.g., valve issues, head gasket leaks) may be necessary.