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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, vacuum gauge, fuel injector cleaning kit.
• Disconnect the negative terminal of the battery to prevent electrical shorts.

2. Replace Spark Plug

1. Remove the engine cover if necessary to access the spark plugs.
2. Using a socket wrench, remove the spark plug from cylinder 1.
3. Inspect the old spark plug for signs of wear or damage; replace with a new spark plug if necessary.
   • Torque Specification: 13 lb-ft (18 Nm) when installing the new spark plug.
4. Reinstall the spark plug and reconnect any components removed.

3. Inspect and Replace Ignition Coil

1. Remove the ignition coil from cylinder 1 by disconnecting the electrical connector and unscrewing the mounting bolts.
2. Test the coil by using a multimeter to check for proper resistance; replace if out of spec.
3. Install a new or tested ignition coil and ensure it is securely fastened.

4. Check Fuel Injector

1. Disconnect the fuel injector connector for cylinder 1.
2. Using a fuel injector cleaning kit, perform a cleaning procedure on the injector.
3. Reconnect the fuel injector and electrical connector, ensuring a secure fit.

5. Compression Test

1. Remove the spark plug from cylinder 1 to facilitate compression testing.
2. Insert the compression tester into the spark plug hole and crank the engine.
3. Record the reading; it should be within the manufacturer's specifications (typically around 150-200 psi).
4. If compression is low, further investigation into piston rings or valves may be necessary.