what are common causes for P0303 misfire code in BMW 5 Series F10/F11 (2010-2017)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the engine is cool before beginning work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench.
• Remove the ignition coil from cylinder 3:
  1. Disconnect the electrical connector from the ignition coil.
  2. Remove the bolts securing the ignition coil and gently pull it out.
• Remove the spark plug:
  1. Use a spark plug socket to unscrew the spark plug from cylinder 3.
  2. Inspect the spark plug for wear or fouling; replace if necessary.
• Install a new spark plug:
  1. Apply anti-seize compound to the threads of the new spark plug.
  2. Hand-tighten the spark plug, then torque it to the manufacturer’s specifications (typically around 15 lb-ft).
• Reinstall the ignition coil:
  1. Place the ignition coil back into the cylinder and secure it with the bolts.
  2. Reconnect the electrical connector.

3. Check and Replace Ignition Coil (if necessary)

• If the spark plug is in good condition, inspect the ignition coil:
  1. Swap the ignition coil from cylinder 3 with another cylinder (e.g., cylinder 1).
  2. Clear the P0303 code and test drive the vehicle to see if the misfire moves to the other cylinder.
• If the misfire moves, replace the ignition coil for cylinder 3 with a new one.
  • Reinstall the ignition coil as previously instructed.

4. Inspect and Clean Fuel Injector

• Tools Required: Fuel injector cleaning kit or replacement injector.
• If the ignition components are functioning properly, check the fuel injector:
  1. Disconnect the fuel line and electrical connector to the fuel injector.
  2. Remove the fuel injector using the appropriate tools.
  3. Clean the injector with a cleaning solution or replace it with a new one.
  4. Reinstall the injector and reconnect the fuel line and electrical connector.