how to fix P0301 code in BMW 3 Series E90/E91 (2005-2012)

Solution

1. Preparation

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

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector on cylinder 1.
• Remove the ignition coil by unscrewing the retaining bolts and pulling it out.
• Using a spark plug socket, remove the old spark plug.
• Inspect the old spark plug for wear (replace if necessary).
• Insert the new spark plug and torque it to the manufacturer's specifications (typically around 18-22 ft-lbs).
• Reinstall the ignition coil and connect the electrical connector.

3. Replace Ignition Coil (if necessary)

• If the ignition coil was found faulty during inspection, replace it.
• Tools Required: Socket set, torque wrench.
• Remove the old ignition coil from cylinder 1 as described above.
• Install the new ignition coil and torque it to specifications.
• Reconnect the ignition coil connector.

4. Clean or Replace Fuel Injector

• If the fuel injector for cylinder 1 is clogged, either clean it or replace it.
• Tools Required: Fuel injector cleaning kit or replacement injector, socket set.
• Disconnect fuel lines and electrical connectors from the injector.
• Remove the injector from the intake manifold.
• Clean the injector using a cleaning kit or install a new injector.
• Reinstall the injector, reconnect fuel lines and electrical connectors.

5. Final Assembly

• Reinstall any components removed for access, including the engine cover.
• Reconnect the battery.