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

Solution

1. Preparation

• Gather the necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shock.

2. Inspect and Replace Spark Plug

• Tools: Socket set, torque wrench.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector from cylinder 2.
• Remove the ignition coil using the socket set.
• Remove the spark plug from cylinder 2 with the spark plug socket.
• Inspect the spark plug for wear and carbon buildup; replace if necessary. Ensure the gap is set according to manufacturer specifications (typically 0.032-0.036 inches).
• Reinstall the new spark plug by hand, then torque to specifications (usually around 15 ft-lbs).

3. Inspect and Replace Ignition Coil

• If the spark plug is in good condition, check the ignition coil for damage.
• If necessary, replace the ignition coil for cylinder 2 with a new one.
• Reinstall the ignition coil and connect the electrical connector securely.

4. Fuel Injector Service

• If misfire persists, check the fuel injector for cylinder 2.
• Disconnect the electrical connector from the fuel injector.
• Remove the fuel injector using appropriate tools (may require special tools).
• Clean or replace the fuel injector if clogged or malfunctioning.
• Reinstall the injector, ensuring it seats correctly, and reconnect the electrical connector.

5. Reassemble and Test

• Reconnect the battery.
• Start the engine and let it idle to check for any misfires.
• Clear the trouble codes using the OBD-II scanner and perform a test drive to ensure the issue is resolved.