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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, gap gauge.
• Remove the engine cover to access the spark plugs.
• Use the socket set to remove the spark plug from cylinder 1.
  • Inspect the spark plug for wear, carbon buildup, or damage.
• If necessary, replace the spark plug with a new one that meets OEM specifications (typically NGK or Bosch).
• Ensure the gap is set correctly according to the manufacturer's specifications (usually around 0.030 inches).
• Reinstall the spark plug and tighten to the specified torque (typically around 20 Nm).

3. Test and Replace Ignition Coil

• Tools Required: Multimeter, socket set.
• Remove the ignition coil from cylinder 1 by unfastening bolts and disconnecting the electrical connector.
• Test the ignition coil with a multimeter for resistance and functionality.
  • If the resistance is out of specification, replace the ignition coil with a new one.
• Reinstall the ignition coil securely and reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

• Tools Required: Fuel injector cleaner, noid light (optional).
• Disconnect the fuel injector connector for cylinder 1.
• Check the injector's electrical connector for continuity using a multimeter.
• If it is faulty, replace the fuel injector with a new one.
• If the injector is operational, clean it using a fuel injector cleaner.
• Reconnect the fuel injector and ensure it is seated properly.

5. Perform Compression Test

• Tools Required: Compression gauge.
• Remove spark plugs from all cylinders for testing.
• Insert the compression gauge into cylinder 1 and crank the engine.
• Compare the reading with manufacturer specifications (usually around 150-200 psi).
• If the compression is low, further investigation is required for possible internal engine problems.