how to fix P0301 misfire code on BMW 3 Series G20/G21 (2019-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester, fuel pressure gauge, vacuum gauge.
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Replace Ignition Coil (if faulty)

• Remove the engine cover if necessary to access the ignition coils.
• Disconnect the electrical connector from the ignition coil on cylinder 1.
• Remove the bolt securing the ignition coil using a socket set.
• Gently pull the ignition coil out of the spark plug hole.
• Install the new ignition coil by reversing the removal steps, ensuring it is seated properly.
• Torque the ignition coil bolt to the manufacturer's specifications (usually around 10 Nm).

3. Replace Spark Plug (if worn)

• Using a spark plug socket, remove the spark plug from cylinder 1.
• Inspect the spark plug for signs of wear or damage (e.g., carbon buildup, worn electrodes).
• Install a new spark plug, ensuring it is gapped according to manufacturer specifications (typically 0.028-0.032 inches).
• Torque the spark plug to the manufacturer's specifications (usually around 25 Nm).

4. Check and Repair Vacuum Leaks

• Inspect all vacuum hoses connected to the intake manifold for cracks or loose connections.
• Use a vacuum gauge to check the intake manifold pressure; a low reading may indicate a leak.
• Replace any damaged hoses or fittings as necessary.

5. Inspect Fuel Injector

• If the injector is suspected to be faulty, remove it from cylinder 1 and visually inspect it for clogs or damage.
• Test the injector's electrical connection with a multimeter to ensure it receives the correct voltage.
• If faulty, replace the fuel injector with a new one, ensuring proper seating and connection.