what does the P0301 code mean for my BMW 3 Series E90/E91 (2005-2012)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.
• Allow the engine to cool before starting the work.

2. Inspect and Replace Spark Plug

1. Remove the ignition coil from cylinder 1.
   • Tools: Socket wrench, extension, and spark plug socket.
2. Extract the spark plug and inspect for wear, carbon buildup, or damage.
3. If necessary, replace with a new spark plug that meets manufacturer specifications.
   • Torque the new spark plug to the manufacturer’s recommended value (typically around 18-22 ft-lbs).

3. Inspect and Replace Ignition Coil

1. If the spark plug is in good condition, test the ignition coil for proper function; replace if faulty.
   • Tools: Multimeter to check coil resistance.
2. Install the new ignition coil onto cylinder 1.
   • Ensure it clicks into place and reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

1. If misfire persists, remove the fuel injector for cylinder 1.
   • Tools: Fuel injector removal tool, socket set.
2. Clean the injector using a specialized fuel injector cleaner or replace it if it is malfunctioning.
3. Reinstall the injector and ensure all connections are secure.

5. Final Checks

1. Reconnect the battery and start the engine.
2. Allow the engine to reach operating temperature and check for any new codes or misfires.