how to diagnose P0301 misfire code on my Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the engine is cool and disconnect the negative battery cable to prevent electrical shock.

2. Replace Spark Plug and Ignition Coil

• Tools Required: Socket set, torque wrench, spark plug socket.
• Instructions:
  1. Remove the engine cover if applicable.
  2. Disconnect the ignition coil connector for cylinder 1.
  3. Remove the bolt securing the ignition coil and gently pull it out.
  4. Remove the spark plug using a spark plug socket.
  5. Inspect the old spark plug and replace it with a new one, torquing it to the manufacturer's specification (typically around 13 lb-ft).
  6. Install the new ignition coil and reconnect the connector.

3. Test and Replace Fuel Injector (if necessary)

• Tools Required: Fuel pressure gauge, injector puller tool.
• Instructions:
  1. Connect a fuel pressure gauge to the fuel rail to check fuel pressure; it should meet OEM specifications (typically around 43-50 psi).
  2. If pressure is low, check for blockages in the fuel filter or lines.
  3. If the injector is faulty, unplug the electrical connector and remove the injector using the injector puller tool.
  4. Install a new fuel injector and reconnect the wiring harness.

4. Reassemble and Clear Codes

• Instructions:
  1. Reinstall any components removed during the repair.
  2. Reconnect the negative battery cable.
  3. Use the OBD-II scanner to clear the P0301 code.