my Toyota Corolla E210 (2019-2024) has a check engine light with code P0301

Solution

1. Preparation

• Gather the necessary tools and parts.
• Disconnect the negative terminal of the battery to ensure safety.
• Allow the engine to cool down before beginning work.

2. Inspect and Replace Spark Plug (if necessary)

• Remove the ignition coil from cylinder 1:
  • Unscrew the retaining bolts with a socket wrench.
  • Lift the coil straight out of the cylinder head.
• Remove the spark plug using a spark plug socket:
  • Turn counterclockwise to remove.
  • Inspect the spark plug for wear, carbon buildup, or oil fouling.
• Replace the spark plug if it is worn or damaged:
  • Install the new spark plug by hand, turning clockwise.
  • Torque to manufacturer specifications (typically around 13-15 lb-ft).
• Reinstall the ignition coil, securing it with the retaining bolts.

3. Inspect and Replace Ignition Coil (if necessary)

• If the ignition coil is damaged:
  • Replace it with a new ignition coil.
  • Ensure the new coil matches the specifications for the Toyota Corolla E210.

4. Check Fuel Injector (if necessary)

• If the injector is faulty:
  • Disconnect the fuel line and electrical connector from the injector.
  • Remove the fuel injector using the appropriate tool.
  • Replace it with a new fuel injector, ensuring proper sealing.

5. Final Assembly

• Reconnect any components or lines you removed during inspection or replacement.
• Reconnect the negative battery terminal.