how to fix P0302 misfire code on BMW 3 Series E90/E91 (2005-2012)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the engine is cool before starting work.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil from cylinder 2.
• Unscrew the old spark plug using the spark plug socket.
• Inspect the old spark plug for signs of wear or damage.
• Install a new spark plug, tightening it to the manufacturer's specified torque (typically around 20-30 Nm).
• Reinstall the ignition coil.

3. Replace Ignition Coil (if necessary)

• If the ignition coil appears damaged or was previously replaced, proceed with replacement.
• Tools Required: Socket set.
• Remove the screws securing the ignition coil to the valve cover.
• Disconnect the electrical connector from the ignition coil.
• Install the new ignition coil, ensuring it sits firmly in place and reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

• Tools Required: Fuel injector cleaning kit or compressed air.
• Disconnect the fuel injector connector.
• Remove the fuel injector from the intake manifold.
• Clean the injector using a cleaning kit or compressed air to clear any blockages.
• Reinstall the fuel injector securely.

5. Verify Compression (if necessary)

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 2.
• Insert the compression tester into the spark plug hole.
• Crank the engine to take a reading and compare it to the manufacturer's specifications.
• If compression is below specifications, further engine diagnostics may be required.