my Toyota Corolla E170 (2013-2019) has a check engine light with code P0301, what's the fix

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 shocks.

2. Inspect and Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench, dielectric grease.
• Remove the engine cover if applicable.
• Locate the spark plug for cylinder 1.
• Remove the ignition coil by unscrewing the mounting bolts and disconnecting the electrical connector.
• Unscrew the spark plug using the spark plug socket.
• Inspect the spark plug for wear; if damaged or worn, replace it with a new one.
• Apply a small amount of dielectric grease to the new spark plug’s threads.
• Install the new spark plug and torque it to the manufacturer’s specification (typically around 13-15 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil

• Tools Required: Socket set, ratchet, torque wrench.
• If the spark plug was not the issue, remove the ignition coil from cylinder 1 as previously discussed.
• Inspect the coil for cracking or carbon tracking.
• If damaged, replace the ignition coil with a new one.
• Reinstall the ignition coil and ensure it is securely fastened.

4. Fuel Injector Inspection

• Tools Required: Fuel injector cleaner, safety goggles, gloves.
• If the ignition components are functioning correctly, check the fuel injector for cylinder 1.
• Disconnect the fuel injector connector and remove the fuel injector.
• Clean the injector using a fuel injector cleaner.
• Reinstall the fuel injector and reconnect the electrical connector.