how to fix P0304 code in Toyota Corolla E210 (2019-2024) misfire issues

Learn how to diagnose and fix P0304 cylinder 4 misfire in Toyota Corolla E210 (2019-2024). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug gap tool
• Remove the ignition coil by unscrewing the bolts and disconnecting the electrical connector.
• Unscrew the spark plug using a spark plug socket.
• Check the gap on the new spark plug and adjust if necessary.
• Install the new spark plug and torque to the manufacturer’s specifications (typically around 13-15 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Inspect/Replace Ignition Coil

• Tools Required: Socket set
• Remove the ignition coil from cylinder 4 as described above.
• Test the ignition coil with a multimeter to check for primary and secondary resistance.
• If faulty, replace the ignition coil with a new unit.
• Reinstall the ignition coil and ensure it is secured properly.

4. Test Fuel Injector

• Tools Required: Fuel injector cleaning kit or multimeter
• Disconnect the fuel injector connector for cylinder 4.
• Use a multimeter to check for proper voltage and resistance.
• If the injector is faulty, replace it with a new one and ensure proper installation.
• Reconnect the fuel injector connector.

5. Perform Compression Test (if necessary)

• Tools Required: Compression tester
• Remove the spark plug and install the compression tester.
• Crank the engine for several revolutions and read the compression value.
• Compare the reading to the engine specifications (typically 180-220 psi).
• If compression is low, further diagnosis may be required (e.g., valve issues, head gasket).