how to fix P0304 code on my Toyota Corolla E140 (2006-2013)

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

Solution

1. Preparation

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

2. Replace Spark Plug

1. Remove the ignition coil from cylinder 4 by unscrewing it from the engine.
2. Remove the spark plug using a spark plug socket and ratchet.
3. Inspect the old spark plug for damage or wear; replace if necessary.
4. Insert the new spark plug and tighten it to the manufacturer's torque specification (typically around 13-16 ft-lbs).
5. Reinstall the ignition coil and connect it securely.

3. Inspect and Replace Ignition Coil (if necessary)

1. If the ignition coil appears damaged, remove it from the engine.
2. Install the new ignition coil by aligning it with the spark plug and securing it with bolts.
3. Reconnect any electrical connectors to the ignition coil.

4. Check Fuel Injector

1. Disconnect the fuel injector connector for cylinder 4.
2. Use a multimeter to test the injector for resistance (should typically be around 12-16 ohms).
3. Replace the fuel injector if it is out of specification, following the manufacturer’s guidelines.

5. Compression Test

1. Remove the spark plug from cylinder 4 and install the compression tester.
2. Crank the engine to get a reading. It should be within the manufacturer’s specified range (usually around 180-200 psi).
3. If compression is low, further engine diagnostics may be needed.