my BMW X3 G01 (2018-2024) has a check engine light with code P0303, what does that mean?

Solution

1. Preparation

• Gather required tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before starting work.

2. Inspect and Replace Ignition Components

• Tools Required: Socket set, torque wrench, ratchet, spark plug socket
• Remove the engine cover if necessary.
• Sub-steps:
  1. Remove the ignition coil for cylinder 3 by unbolting it and disconnecting the electrical connector.
  2. Remove the spark plug from cylinder 3 using a spark plug socket.
  3. Inspect the spark plug for wear; replace if necessary (gap should be between 0.028-0.031 inches).
  4. Install a new spark plug and torque to specification (approximately 18 ft-lbs).
  5. Reinstall the ignition coil and ensure the electrical connection is secure.

3. Check and Clean Fuel Injector

• Tools Required: Fuel injector cleaner, basic hand tools
• Sub-steps:
  1. Disconnect the fuel injector harness and remove the injector from cylinder 3.
  2. Inspect for clogs or debris; use fuel injector cleaner to flush the injector if necessary.
  3. Reinstall the injector ensuring proper seating and connection.

4. Compression Test

• Tools Required: Compression tester
• Sub-steps:
  1. Remove all spark plugs to allow for accurate compression testing.
  2. Insert the compression tester into the spark plug hole for cylinder 3.
  3. Crank the engine for a few seconds and record the compression reading.
  4. Compare results with the manufacturer specifications (typically 140-200 psi).
  5. If readings are low, further investigation into the piston rings or valves may be necessary.