how to diagnose P0301 code on my BMW 3 Series G20/G21 (2019-2024)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid electrical shorts.
• Allow the engine to cool if it has been running.

2. Replace Spark Plug

• Remove Spark Plug: Use a spark plug socket and ratchet to remove the spark plug from cylinder 1.
• Install New Spark Plug: Apply anti-seize compound on the threads of the new spark plug, torque it to the manufacturer's specification (typically 18-22 lb-ft), and reattach the ignition coil.

3. Replace Ignition Coil

• Remove Ignition Coil: Disconnect the electrical connector and remove the bolts securing the ignition coil for cylinder 1.
• Install New Ignition Coil: Position the new coil in place, tighten the bolts to the specified torque, and reconnect the electrical connector.

4. Clean or Replace Fuel Injector

• Inspect Fuel Injector: If necessary, remove the fuel injector from cylinder 1.
• Clean or Replace: Clean the injector using an ultrasonic cleaner or replace it if it’s faulty. Reinstall the injector and connect any necessary lines.

5. Perform Compression Test

• Conduct Test: If compression is low, further investigate engine internals (e.g., valve seals, piston rings). If compression is normal, proceed with reassembly.