how to address a P0302 misfire code in my BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester, spark plug socket, and replacement parts.
• Safety Warnings: Disconnect the battery before working on electrical systems.

2. Replace Spark Plug

• Remove the ignition coil cover to access the spark plugs.
• Use a socket wrench to remove the spark plug from cylinder 2.
• Inspect the old spark plug; if worn or damaged, install a new spark plug with the correct specifications (usually NGK or Bosch for BMW).
• Torque the spark plug to the manufacturer’s specification (typically around 20 Nm).

3. Test/Replace Ignition Coil

• Remove the ignition coil from cylinder 2.
• If previously swapped for testing, check if the misfire follows the coil to a different cylinder.
• If faulty, replace the ignition coil with a new OEM part.
• Reinstall the ignition coil and ensure it is seated properly.

4. Inspect/Replace Fuel Injector

• Disconnect the fuel injector connector for cylinder 2.
• Use a multimeter to check if the injector is receiving the correct voltage when the ignition is turned on.
• If the injector is clogged or not firing, replace it with a new unit and reconnect the electrical connector.

5. Compression Test

• If misfire persists, perform a compression test on cylinder 2.
• If compression is lower than the specified range (typically around 150-200 psi for BMW), further investigation into internal engine issues may be necessary.