how to fix P0300 misfire code in BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plugs

• Tools Required: Spark plug socket, ratchet, torque wrench.
• Remove the ignition coils to access the spark plugs.
• Inspect each spark plug for wear and carbon buildup; replace if necessary.
• Install new spark plugs, ensuring they are gapped correctly according to manufacturer specifications. Torque to the specified value (typically around 22 lb-ft).

3. Inspect and Replace Ignition Coils

• Check each ignition coil for cracks or signs of overheating.
• If any coils are faulty, remove and replace with new coils.
• Reinstall the ignition coils and ensure they are seated properly.

4. Fuel System Inspection

• Tools Required: Fuel pressure gauge.
• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (without starting the engine) to check for proper fuel pressure.
• If the pressure is low, inspect the fuel pump and filter for blockages or failures. Replace as necessary.

5. Vacuum Leak Inspection

• Visually inspect all vacuum lines and hoses for cracks or disconnections.
• Use a smoke machine if available to detect hidden vacuum leaks.
• Replace any damaged hoses or components.

6. Compression Test

• Tools Required: Compression tester.
• Remove spark plugs and connect the compression tester to each cylinder.
• Crank the engine and record the compression readings. All cylinders should have similar readings within the manufacturer’s specifications.
• If compression is low in any cylinder, further investigation into valve seals or piston rings may be necessary.