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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical short circuits during repair.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket, gap gauge.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector.
• Remove the ignition coil from cylinder 1.
• Remove the spark plug using the spark plug socket.
• Inspect the spark plug for wear or damage, and replace it if necessary.
• Check and adjust the spark plug gap according to manufacturer specifications (typically around 0.030-0.035 inches).
• Reinstall the spark plug and ignition coil, ensuring proper torque (typically 18-22 lb-ft for spark plugs).

3. Inspect and Replace Ignition Coil

• Tools Required: Socket set.
• If the ignition coil appears damaged or has high resistance, replace it.
• Remove the faulty ignition coil and install the new one.
• Reconnect the ignition coil connector.

4. Check and Replace Fuel Injector

• Tools Required: Fuel line disconnect tool, socket set.
• If the fuel injector is faulty, remove the fuel rail to access the injector.
• Disconnect the fuel lines (relieve fuel pressure first).
• Remove the injector and replace it with a new one.
• Reassemble the fuel rail and ensure all connections are secure.

5. Perform Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 1.
• Insert the compression tester and crank the engine to obtain a reading.
• Compare the reading to the manufacturer's specifications. If low, further investigation is required.