how to identify if my BMW 5 Series G30/G31 (2017-2024) needs a new alternator?

Solution

1. Preparation

• Gather tools: socket set, multimeter, OBD-II scanner, wrench set, and safety goggles.
• Disconnect the negative terminal of the battery to prevent electrical shock.
• Allow the engine to cool before proceeding.

2. Remove Alternator

• 1.1 Remove the engine cover (if applicable) by unscrewing or unclipping it.
• 1.2 Detach the serpentine belt from the alternator pulley using a wrench to relieve tension.
• 1.3 Remove the electrical connectors from the alternator by gently pulling them off.
• 1.4 Unbolt the alternator from its mounting using the appropriate socket size.
• 1.5 Carefully lift the alternator out of the engine bay.

3. Install New Alternator

• 2.1 Position the new alternator into the mounting bracket and secure it with bolts, tightening to manufacturer specifications (typically around 30 Nm).
• 2.2 Reattach the electrical connectors to the new alternator, ensuring they click into place.
• 2.3 Reinstall the serpentine belt onto the alternator pulley, ensuring it is properly aligned with all pulleys.
• 2.4 Reattach the engine cover if it was removed.
• 2.5 Reconnect the negative battery terminal.

4. Final Checks

• 3.1 Start the engine and verify the battery voltage with a multimeter; it should be between 13.7 to 14.7 volts.
• 3.2 Check that all electrical systems are functioning properly (headlights, interior lights, etc.).
• 3.3 Inspect for any unusual noises from the alternator area.