how to diagnose and fix P0301 code in my BMW 5 Series G30/G31 (2017-2024)?

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, fuel injector tester, multimeter, vacuum gauge.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Replace Spark Plug and Ignition Coil

1. Disconnect the negative battery terminal to prevent electrical shorts.
2. Remove the engine cover if applicable.
3. Remove the ignition coil from cylinder 1 by unbolting it and disconnecting the electrical connector.
4. Remove the spark plug using a spark plug socket and ratchet.
5. Inspect the old spark plug for signs of fouling or wear.
6. Install the new spark plug, hand-tightening it before torquing it to the manufacturer’s specified torque (usually around 15-20 lb-ft).
7. Reinstall the ignition coil and connect the electrical connector securely.

3. Test and Replace Fuel Injector (if necessary)

1. If the fuel injector was found to be faulty during diagnostics, disconnect the negative battery terminal again.
2. Remove the fuel rail by detaching any retaining bolts and carefully lifting it, ensuring not to damage the fuel lines.
3. Pull out the fuel injector from cylinder 1, ensuring the O-ring comes out with it.
4. Install the new fuel injector, applying a small amount of clean engine oil to the O-ring for proper sealing.
5. Reinstall the fuel rail and ensure it is secure.

4. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0301 code from the vehicle's computer.
3. Perform a test drive to monitor for any reoccurrence of the error code.