how to diagnose BMW 5 Series G30/G31 (2017-2024) with P0301 misfire code?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool if it has been running.

2. Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench, gap gauge.
• Remove the spark plug from cylinder 1 using the spark plug socket.
• Inspect the gap and condition of the spark plug. If worn, replace with a new spark plug, ensuring it is gapped to manufacturer specifications (usually around 0.028-0.032 inches).
• Reinstall the spark plug and torque it to the manufacturer’s specification (typically around 20 Nm).

3. Inspect and Replace Ignition Coil (if necessary)

• Tools Required: Socket set, torque wrench.
• Remove the ignition coil from cylinder 1 by disconnecting the electrical connector and unscrewing the mounting bolts.
• If the coil is faulty, replace it with a new one, ensuring the connection is secure, and torque it to the specified value (around 10 Nm).

4. Test and Replace Fuel Injector (if necessary)

• Tools Required: Fuel injector cleaning kit or replacement injector.
• Disconnect the fuel injector connector from cylinder 1.
• Use a multimeter to test the electrical resistance of the injector according to specifications (usually around 12-16 ohms).
• If faulty, replace the injector, ensuring to lubricate the O-ring with clean engine oil before installation. Torque to specifications (usually around 15 Nm).

5. Conduct Compression Test

• Tools Required: Compression tester.
• Remove the spark plug from cylinder 1 and connect the compression tester.
• Crank the engine and record the compression reading. Compare it to the manufacturer’s specifications (typically around 180-200 psi).
• If compression is low, further investigation into potential internal engine issues may be required.