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

Solution

1. Preparation

• Gather 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 shorts.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil from cylinder 1.
  • Unplug the electrical connector from the ignition coil.
  • Remove the mounting bolt using a socket.
  • Pull the ignition coil out gently.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear or damage (excessive carbon buildup, wear on the electrode).
• If necessary, replace the spark plug with a new one (OEM recommended).
  • Torque the new spark plug to the manufacturer's specification (typically around 13-16 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Check and Clean Fuel Injector

• Tools Required: Fuel injector cleaner kit, basic hand tools.
• Remove the fuel injector from cylinder 1.
  • Relieve fuel pressure by removing the fuel pump fuse and running the engine until it stalls.
  • Disconnect the fuel line from the injector (be cautious of residual fuel).
  • Remove the fuel injector mounting clips and pull out the injector.
• Clean the fuel injector with a fuel injector cleaner or replace it if it is clogged or damaged.
• Reinstall the fuel injector, ensuring proper seating and reattach the fuel line and clips.

4. Conduct Compression Test

• Tools Required: Compression gauge.
• Remove the spark plugs from all cylinders.
• Insert the compression gauge into the spark plug hole of cylinder 1.
• Crank the engine for a few seconds and record the pressure.
• Compare the reading with the manufacturer's specifications (typically around 150-200 psi). If the compression is low, further investigation into valve seals or piston rings may be necessary.