how to fix P0301 code on BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather necessary tools and ensure the vehicle is parked on a flat surface.
• Disconnect the battery's negative terminal to prevent electrical shorts.
• Tools required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, and screwdrivers.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 1:
  1. Remove any covers obstructing access to the ignition coil.
  2. Disconnect the electrical connector from the ignition coil.
  3. Unscrew the ignition coil and carefully pull it out.
• Remove the spark plug:
  1. Use a spark plug socket to remove the spark plug from cylinder 1.
  2. Inspect the spark plug for wear, carbon buildup, or damage.
  3. If necessary, replace the spark plug with a new one, ensuring it is gapped according to the manufacturer’s specifications (usually around 0.032-0.036 inches).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Test and Replace Ignition Coil

• If the spark plug is in good condition, test the ignition coil:
  1. Use a multimeter to check the primary and secondary resistance values against the specifications in the service manual.
• If the ignition coil is faulty, replace it with a new one.
• Reinstall all components and reconnect the battery.

4. Check Fuel Injector

• If the misfire persists, test the fuel injector for cylinder 1:
  1. Disconnect the fuel injector connector and use a multimeter to check for continuity.
  2. If the injector is not functioning properly, replace it with a new one.
• Reconnect all connectors and perform a functional test.

5. Compression Test

• If issues remain, conduct a compression test on cylinder 1:
  1. Remove the spark plug and connect the compression tester.
  2. Crank the engine and record the compression reading.
  3. Compare the reading to the manufacturer's specifications (typically around 140-200 psi).
• If compression is low, further diagnosis may be needed to investigate valve or piston issues.