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

Solution

1. Preparation

• Gather tools and parts required for repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery cable to avoid electrical hazards.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug gap tool
• Remove the ignition coil for cylinder 3:
  1. Unplug the electrical connector from the ignition coil.
  2. Remove the bolt securing the ignition coil and gently pull it out.
• Remove the spark plug:
  1. Use the socket set to remove the spark plug from cylinder 3.
  2. Inspect the spark plug for wear or carbon fouling; replace if necessary.
• Install a new spark plug:
  1. Gap the new spark plug according to manufacturer specifications.
  2. Install the spark plug by hand first, then torque to the specified value (usually around 20 Nm).

3. Inspect and Replace Ignition Coil

• If the spark plug is in good condition, inspect the ignition coil:
  1. Visually check for cracks or damage.
  2. Test the resistance of the ignition coil using a multimeter.
• Replace the ignition coil if it shows signs of failure:
  1. Install the new ignition coil in place of the old one.
  2. Reconnect the electrical connector and secure it with the bolt.

4. Inspect Fuel Injector

• If the misfire persists, check the fuel injector:
  1. Disconnect the fuel injector connector.
  2. Use a noid light to check for proper signal; replace if there's no signal.
  3. If signal is present, use a fuel pressure gauge to check injector operation.
• Replace the fuel injector if it is faulty:
  1. Remove the fuel rail if necessary to access the injector.
  2. Install the new fuel injector and reconnect all electrical connectors.

5. Reassemble and Test

• Reconnect all components, including the negative battery cable.
• Clear the DTCs using the OBD-II scanner.
• Start the engine and let it idle to ensure smooth operation.