how to fix P0301 misfire code in my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather all tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface with the engine off and cool.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 1 by unscrewing the retaining bolt and disconnecting the electrical connector.
• Remove the spark plug using a spark plug socket and ratchet.
• Inspect the spark plug for wear (electrode condition, gap) and replace if necessary with the manufacturer's recommended part.
• Reinstall the spark plug and torque it to the manufacturer's specification (typically 13-16 ft-lbs).
• Reinstall the ignition coil, ensuring it is seated properly and reconnect the electrical connector.

3. Check and Replace Ignition Coil

• If the spark plug is in good condition, test the ignition coil for proper resistance using a multimeter. If it is outside the manufacturer’s specified range, replace the ignition coil.
• Remove the old ignition coil and install the new one, ensuring it is properly connected to the spark plug and electrical connector.

4. Test or Replace Fuel Injector

• If misfires persist, test the fuel injector for cylinder 1 using a noid light to check for proper pulse.
• If the injector is faulty, remove the fuel rail (after relieving fuel pressure) and replace the injector.
• Reassemble the fuel rail and reconnect any hoses and electrical connectors.

5. Verify Cylinder Compression

• If all components appear functional, perform a compression test on cylinder 1.
• If compression is low, further diagnostics will be needed to assess potential internal engine issues.