why does my BMW 3 Series G20/G21 (2019-2024) have a check engine light with code P0300

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the electrical components.
• Allow the engine to cool down if it was previously running.

2. Inspect and Replace Ignition Components

• Inspect Spark Plugs

  • Remove spark plug wires and unscrew the spark plugs using a spark plug socket.
  • Inspect for wear or fouling. Replace if necessary with OEM equivalent plugs.

• Inspect Ignition Coils

  • Remove ignition coils by disconnecting the electrical connectors and unscrewing the mounting bolts.
  • Check for cracks or damage. Replace if faulty.

3. Check Fuel System

• Check Fuel Pressure
  • Connect a fuel pressure gauge to the fuel rail.
  • Turn the ignition to the ON position without starting the engine and check for proper fuel pressure as specified in the service manual.
  • If pressure is low, inspect the fuel pump and filter for blockages and replace if necessary.

4. Air Intake System Inspection

• Inspect for Leaks
  • Visually inspect all intake hoses and the throttle body for cracks or loose fittings.
  • Replace any damaged hoses.

5. Vacuum System Check

• Inspect Vacuum Lines
  • Check all vacuum lines for cracks, leaks, or disconnections.
  • Replace any damaged lines to ensure proper engine operation.