my BMW X3 F25 (2011-2018) has a check engine light with code P0303, what's the issue?

Solution

1. Preparation

• Gather tools and parts needed.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to avoid electrical shock.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the engine cover (if applicable) using a socket set.
  2. Locate the spark plug for cylinder 3.
  3. Remove the spark plug wire or ignition coil connector.
  4. Use a spark plug socket to carefully remove the spark plug.
  5. Inspect the spark plug for signs of wear or damage; replace if necessary with the correct part (OEM recommended).

Tools Required: Socket set, spark plug socket, torque wrench
Parts Required: Replacement spark plug

3. Inspect and Replace Ignition Coil

• Sub-steps:
  1. Remove the ignition coil for cylinder 3 by unbolting it (if applicable).
  2. Check the connector for corrosion or damage.
  3. Install the new ignition coil and secure it in place.

Tools Required: Socket set
Parts Required: Replacement ignition coil

4. Inspect and Clean Fuel Injector

• Sub-steps:
  1. Remove the fuel injector connector for cylinder 3.
  2. Disconnect the fuel rail (ensure to relieve fuel pressure beforehand).
  3. Remove the fuel injector from the rail.
  4. Clean the injector using a specialized cleaner or replace it if clogged.
  5. Reinstall the injector and reconnect the fuel rail.

Tools Required: Fuel injector puller, cleaning solution
Parts Required: Replacement fuel injector (if necessary)

5. Reconnect Battery and Test

• Reconnect the battery terminals.
• Start the engine and observe for smooth operation.
• Clear the error codes using an OBD-II scanner.