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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the engine is cool and disconnect the battery to avoid electrical shock.
• Prepare a clean workspace.

2. Replace Spark Plug

1. Remove the ignition coil from cylinder 1 by unscrewing the bolts and disconnecting the electrical connector.
2. Remove the spark plug using a spark plug socket and ratchet.
3. Inspect the old spark plug for wear or damage; compare it with the new one.
4. Install the new spark plug to the manufacturer's torque specification (typically 13-15 lb-ft).
5. Reinstall the ignition coil securely.

3. Inspect and Replace Ignition Coil

1. If the spark plug is in good condition but the misfire persists, test the ignition coil with a multimeter for proper resistance.
2. If faulty, remove the ignition coil from cylinder 1 as described above.
3. Install the new ignition coil, ensuring it is seated correctly and reconnect the electrical connector.

4. Clean or Replace Fuel Injector

1. If the ignition components are functioning well, proceed to inspect the fuel injector for cylinder 1.
2. Disconnect the fuel injector connector and remove the mounting bolts.
3. If cleaning, use a fuel injector cleaner and follow the manufacturer's instructions; if replacing, install the new injector.
4. Reconnect the fuel injector connector securely.

5. Conduct Compression Test

1. If misfire continues, perform a compression test on cylinder 1.
2. Remove the spark plug and connect the compression gauge to the cylinder.
3. Crank the engine and record the reading; compare it to the manufacturer's specifications.
4. If the compression is low, further investigation is needed for potential internal engine damage.