how to fix P0303 code in my Toyota Corolla E140 (2006-2013)?

Learn how to diagnose and fix P0303 cylinder 3 misfire in Toyota Corolla. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, fuel injector cleaner.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery before starting work on electrical components.

2. Replace Spark Plug

• Remove the ignition coil from cylinder 3:
  • Disconnect the electrical connector.
  • Unscrew the bolts securing the coil and lift it out.
• Remove the spark plug:
  • Use a spark plug socket to unscrew the spark plug from the cylinder head.
• Install a new spark plug:
  • Check the gap according to the manufacturer's specifications (typically 0.043 inches for Toyota).
  • Insert the new spark plug and torque it to 13 lb-ft (17.6 Nm).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Replace Ignition Coil (if necessary)

• If the ignition coil is faulty:
  • Remove the coil as described above.
  • Install a new ignition coil and ensure it is seated properly.
  • Reconnect the electrical connector.

4. Clean or Replace Fuel Injector

• If the fuel injector is clogged:
  • Remove the fuel injector from cylinder 3:
    • Disconnect the fuel line and electrical connector.
    • Unscrew the injector retaining clips and gently pull the injector out.
  • Clean the injector with a fuel injector cleaner or replace it if damaged.
  • Reinstall the fuel injector and reconnect all lines and connectors.

5. Perform Compression Test (if necessary)

• If low compression is detected:
  • Follow the manufacturer's specifications for the compression test.
  • If compression is below specifications, further investigation into internal engine problems may be needed.