how to fix the P0301 misfire code in my BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather tools and materials.
• Disconnect the negative battery terminal to avoid electrical shorts.
• Allow the engine to cool if previously running.

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 signs of wear or fouling.
• Install the new spark plug, ensuring it is gapped correctly as per manufacturer specifications (typically around 0.030 inches for BMW).
• Torque the spark plug to the recommended specification (usually around 18-22 Nm).

3. Inspect and Replace Ignition Coil

• Remove the ignition coil connector carefully.
• Unscrew the bolts holding the ignition coil in place and remove it.
• Inspect the ignition coil for cracks or signs of wear.
• If necessary, replace the ignition coil with a new one and securely fasten it.
• Reconnect the ignition coil connector.

4. Check and Replace Fuel Injector

• Disconnect the fuel injector connector.
• Remove the fuel rail if necessary to access the injector.
• Use a fuel injector puller or carefully wiggle the injector out.
• Inspect the injector for clogs or damage.
• Replace it with a new fuel injector if necessary, ensuring proper sealing.
• Reinstall the fuel rail and reconnect the injector connector.

5. Compression Test

• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine a few times and read the compression gauge.
• If the compression is below specifications (typically around 120-140 psi), further investigation is needed (valve issues, head gasket failure, etc.).