how to fix P0301 misfire code on BMW 3 Series F30/F31

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to avoid any electrical shorts.
• Ensure the engine is cool before starting work.

2. Replace Spark Plug

• Remove the engine cover if applicable.
• Use a socket wrench to remove the spark plug from cylinder 1.
• Inspect the old spark plug for wear or carbon buildup.
• Install a new spark plug (OEM recommended gap) and tighten to manufacturer specifications (typically around 15 ft-lbs).

3. Replace Ignition Coil

• Disconnect the electrical connector from the ignition coil on cylinder 1.
• Remove the bolts securing the ignition coil and pull it out gently.
• Install the new ignition coil and secure it with bolts to the specified torque.
• Reconnect the electrical connector.

4. Clean or Replace Fuel Injector

• If cleaning, use an appropriate fuel injector cleaner and follow the instructions.
• If replacing, disconnect the fuel line (safety: relieve fuel pressure first).
• Remove the fuel injector from cylinder 1 by releasing the retaining clips and pulling it out.
• Install the new or cleaned fuel injector and reconnect the fuel line.

5. Check Compression

• Attach the compression tester to the spark plug hole of cylinder 1.
• Crank the engine and record the compression reading.
• If the reading is below specifications (typically around 150 psi), further investigation into internal engine issues is required.