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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery negative terminal to ensure safety.
• Allow the engine to cool before beginning work.

2. Replace Ignition Coil

• Tools Required: Socket set, torque wrench.
• Remove the engine cover if applicable.
• Disconnect the electrical connector from the ignition coil on cylinder 2.
• Remove the bolt securing the ignition coil with a socket.
• Pull out the ignition coil from the spark plug well.
• Install the new ignition coil by reversing the removal steps. Torque the bolt to manufacturer specifications (usually around 10 Nm).

3. Replace Spark Plug

• Tools Required: Spark plug socket, torque wrench.
• Remove the ignition coil as described above.
• Use a spark plug socket to unscrew and remove the old spark plug from cylinder 2.
• Inspect the old spark plug for signs of wear or fouling.
• Install a new spark plug, ensuring it is gapped to the manufacturer's specifications (typically around 0.028-0.032 inches).
• Torque the spark plug to manufacturer specifications (usually around 25 Nm).

4. Inspect and Clean Fuel Injector

• Tools Required: Fuel injector cleaner, small brush.
• Remove the fuel injector from cylinder 2 using appropriate tools.
• Inspect the injector for blockages or damage.
• Clean the injector using a fuel injector cleaner and a small brush if necessary.
• Reinstall the fuel injector, ensuring it is seated properly.

5. Reassemble and Reconnect

• Reconnect the ignition coil and any other components removed during the process.
• Reattach the engine cover if applicable.
• Reconnect the battery terminal.