how to diagnose a P0304 code on my 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.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Ignition Coil (if faulty)

1. Locate the ignition coil for cylinder 4 (refer to the vehicle's service manual for exact location).
2. Remove the engine cover if necessary using a socket set.
3. Disconnect the electrical connector from the ignition coil.
4. Remove the mounting bolt(s) using a socket wrench.
5. Gently pull the ignition coil out of the spark plug well.
6. Install the new ignition coil by reversing the steps, ensuring it is seated correctly.

3. Replace Spark Plug (if worn or damaged)

1. Using a spark plug socket, remove the spark plug from cylinder 4.
2. Inspect the spark plug for wear or fouling; replace if necessary.
3. Check the gap on the new spark plug (should match manufacturer specifications).
4. Install the new spark plug, torquing to the manufacturer's specifications.
5. Reconnect the ignition coil to the spark plug.

4. Clean or Replace Fuel Injector (if necessary)

1. Remove the fuel injector rail by loosening the bolts and disconnecting the fuel line (use a fuel line disconnect tool if needed).
2. Pull the injector out of the fuel rail.
3. Inspect the injector for clogs; use a fuel injector cleaner or replace if necessary.
4. Reinstall the cleaned or new injector, ensuring O-rings are lubricated with clean engine oil before installation.