how to fix P0301 misfire code in my Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before proceeding with any work.

2. Replace Spark Plug in Cylinder 1

• Remove the ignition coil by disconnecting the electrical connector and unscrewing the mounting bolts.
• Extract the old spark plug using a spark plug socket and ratchet.
• Inspect the spark plug for wear; replace with a new spark plug if necessary (gapping may be required).
• Reinstall the spark plug and torque to manufacturer specifications (typically around 13-16 lb-ft).
• Reattach the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil (if necessary)

• If the ignition coil shows signs of wear or testing reveals failure, remove the faulty ignition coil from cylinder 1.
• Install the new ignition coil ensuring it is seated properly.
• Reconnect any electrical connectors.

4. Check and Clean Fuel Injector

• Remove the fuel injector from cylinder 1, ensuring to relieve the fuel pressure beforehand.
• Inspect the injector for blockages and clean it using a fuel injector cleaner kit or replace it if defective.
• Reinstall the fuel injector and ensure it is properly seated.

5. Conduct a Compression Test

• If misfire persists, perform a compression test on cylinder 1.
• If compression is below specifications (typically around 180-200 psi), further investigation into valve or piston issues may be necessary.

6. Inspect for Vacuum Leaks

• Check all vacuum hoses and intake manifold gaskets for leaks.
• Replace any damaged hoses or gaskets to ensure proper air/fuel mixture.