how to fix P0304 misfire code in Volkswagen Passat B8 (2015-2022)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Volkswagen Passat B8 (2015-2022). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts before starting the repair.
• Disconnect the vehicle's battery to prevent electrical shorts during repair.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil from cylinder 4 by disconnecting the electrical connector and unscrewing the bolts.
• Carefully extract the spark plug using a spark plug socket.
• Inspect the old spark plug for signs of wear or fouling.
• Install a new spark plug, ensuring it is gapped correctly according to the manufacturer's specifications (typically around 0.028-0.032 inches).
• Torque the spark plug to the specified value (usually around 15-25 ft-lbs).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Replace Ignition Coil (if necessary)

• Tools Required: Socket set, torque wrench.
• If the ignition coil is found to be defective, remove it from cylinder 4 as previously described.
• Install a new ignition coil, ensuring it is seated properly.
• Torque the mounting bolts to the specified value (usually around 80-120 in-lbs).

4. Check and Replace Fuel Injector (if necessary)

• Tools Required: Fuel injector puller, socket set.
• If the fuel injector is suspected to be malfunctioning, disconnect the fuel line and electrical connector.
• Remove the injector using a fuel injector puller.
• Install a new fuel injector, ensuring it is seated correctly and properly connected.

5. Final Checks

• Reconnect the battery.
• Start the engine and allow it to reach operating temperature.
• Monitor for any check engine lights or abnormal behavior.