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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plug

• Remove the engine cover (if applicable) using a socket set.
• Locate the spark plug in cylinder 1.
• Use a spark plug socket to carefully remove the old spark plug.
• Inspect the spark plug for wear; if it’s worn or fouled, replace it with a new one.
• Torque the new spark plug to the manufacturer’s specifications (usually around 25 Nm).
• Reinstall the engine cover if removed.

3. Inspect and Replace Ignition Coil

• Disconnect the electrical connector from the ignition coil in cylinder 1.
• Remove the ignition coil using a socket or wrench.
• Inspect the coil for cracks or damage; if defective, replace it with a new one.
• Reinstall the ignition coil and reconnect the electrical connector.
• Repeat for other cylinders if misfires persist.

4. Clean or Replace Fuel Injector

• Remove the fuel injector from cylinder 1 after relieving fuel pressure.
• Inspect the injector for blockages; clean it using a fuel injector cleaner or replace it if necessary.
• Reinstall the injector ensuring proper seating and connection.

5. Perform Compression Test

• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine to obtain the compression reading.
• Compare the reading to manufacturer specifications; replace the piston rings or valves if compression is low.

6. Check for Vacuum Leaks

• Inspect intake manifold and vacuum hoses for cracks or disconnections.
• Use a smoke machine or carburetor cleaner to detect leaks.
• Repair or replace any damaged components.