why does my Toyota Corolla E210 (2019-2024) engine misfire and show P0301 code?

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 1:
  • Unplug the electrical connector.
  • Remove the retaining bolt and lift the coil out.
• Remove the spark plug:
  • Use a spark plug socket and ratchet to unscrew the spark plug.
• Inspect the spark plug for wear or damage; replace if necessary.
• Install a new spark plug:
  • Torque to manufacturer specifications (typically around 13-15 lb-ft).

3. Test and Replace Ignition Coil

• Test the ignition coil for proper resistance using a multimeter:
  • Check the primary and secondary resistance according to specifications (usually 0.4-2.0 ohms for primary and 12,000-20,000 ohms for secondary).
• If out of spec, replace the ignition coil with a new one.
• Reinstall the ignition coil:
  • Position it over the spark plug and secure with the retaining bolt.
  • Reconnect the electrical connector.

4. Check and Replace Fuel Injector

• Disconnect the fuel line from the fuel injector (use caution; a fuel pressure gauge may be necessary).
• Remove the fuel injector from cylinder 1 using the appropriate tool.
• Inspect the injector for clogs or leaks; replace if necessary.
• Install the new fuel injector:
  • Ensure O-rings are lubricated and seated properly.
  • Reconnect the fuel line.

5. Reassemble and Perform Final Checks

• Reconnect the battery terminal.
• Start the engine and allow it to reach operating temperature.
• Clear the P0301 code using the OBD-II scanner.