why does my Volkswagen Passat B8 (2015-2022) have a check engine light with code P0303

Learn how to diagnose and fix P0303 cylinder 3 misfire in Volkswagen Passat B8 (2015-2022). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the vehicle battery to prevent electrical shorts.
• Allow the engine to cool before proceeding with repairs.

2. Inspect and Replace Spark Plug

• Remove the ignition coil cover if applicable.
• Use a socket wrench to remove the spark plug from cylinder 3.
• Inspect the spark plug for damage; replace if fouled or worn (gap specifications: 0.028-0.032 inches).
• Install the new spark plug by hand to prevent cross-threading, then torque to 18 ft-lbs (24 Nm).

3. Check and Replace Ignition Coil

• Disconnect the electrical connector from the ignition coil.
• Remove the ignition coil by pulling it straight out of the spark plug hole.
• Replace with a new ignition coil specific to the Passat B8. Ensure proper seating.
• Reconnect the ignition coil connector.

4. Fuel Injector Inspection

• Remove the fuel rail if needed for access (follow manufacturer instructions).
• Inspect the fuel injector for cylinder 3; ensure it is not clogged or malfunctioning.
• If faulty, replace it with a new fuel injector compatible with the VW Passat B8.
• Reinstall the fuel rail and ensure all connections are secure.

5. Compression Test (if needed)

• If misfire persists, perform a compression test on cylinder 3.
• If the compression is low, inspect for valve issues or a blown head gasket.