how to fix the P0303 code in my BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

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

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil from cylinder 3.
  • Unplug the electrical connector.
  • Remove the retaining bolts and lift off the ignition coil.
• Remove the spark plug using a spark plug socket.
• Inspect the old spark plug; replace if worn or damaged.
• Install the new spark plug, torquing it to the manufacturer’s specified value (typically around 22 Nm).
• Reinstall the ignition coil over the new spark plug and secure it with bolts.

3. Check/Replace Ignition Coil

• If the spark plug is fine, test the ignition coil for cylinder 3.
• If faulty, replace with a new ignition coil.
  • Follow the same steps as above for removal and installation.

4. Clean/Replace Fuel Injector

• If misfire persists, check the fuel injector for cylinder 3.
• Remove the fuel rail to access the injector.
• Clean the injector or replace it if clogged or malfunctioning.
• Reinstall the fuel rail and ensure all connections are secure.

5. Inspect for Vacuum Leaks

• Check all vacuum hoses connected to the intake manifold.
• Replace any cracked or damaged hoses.
• Use a smoke test if necessary to identify leaks.