how to fix P0302 misfire code on BMW 3 Series G20/G21 (2019-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, spark plug socket, compression gauge, fuel injector cleaning kit.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plug

• Remove the engine cover if necessary to access the spark plug.
• Use the spark plug socket to remove the spark plug from cylinder 2.
  • Sub-steps:
    • Check the spark plug for wear or carbon buildup. Replace if necessary, ensuring that the new spark plug is gapped according to manufacturer specifications (usually around 0.030-0.035 inches).
    • Install the new spark plug and torque to the manufacturer's specified value (typically around 15-20 ft-lbs).

3. Inspect and Replace Ignition Coil

• Remove the ignition coil from cylinder 2.
  • Sub-steps:
    • Check for any cracks or carbon tracking on the coil.
    • If damaged, replace the ignition coil with a new one.
    • Reinstall the ignition coil and ensure it is seated properly.

4. Test and Clean Fuel Injector

• Remove the fuel injector from cylinder 2.
  • Sub-steps:
    • Inspect for clogs or leaks; if clogged, use a fuel injector cleaning kit to clean it.
    • If cleaning does not resolve the issue, replace the fuel injector.
    • Reinstall the fuel injector ensuring proper seating and connection.

5. Perform Compression Test

• Conduct a compression test on cylinder 2 to check for mechanical issues.
  • Sub-steps:
    • If the compression is below specification (usually around 120-150 psi), further diagnostics may be required for internal engine issues such as valve problems or head gasket failure.

6. Reassemble and Clear Codes

• Reinstall any components removed during the process.
• Connect the battery and use the OBD-II scanner to clear the P0302 code.