how to diagnose a no-start condition in my BMW 3 Series G20/G21 (2019-2024)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Battery Maintenance

• Inspect and Clean Terminals
  • Remove any corrosion using a wire brush.
  • Ensure connections are tight.
• Charge or Replace Battery
  • If voltage is below 12.4 volts, charge the battery or replace it if it fails to hold a charge.

3. Starter Motor Replacement

• Remove Starter Motor
  • Locate the starter motor (usually near the transmission).
  • Disconnect wiring harness and remove mounting bolts using a socket set.
• Install New Starter Motor
  • Position the new starter motor and secure it with mounting bolts (torque to manufacturer specifications).
  • Reconnect the wiring harness.

4. Electrical System Check

• Inspect and Replace Fuses
  • Locate the fuse box and check for blown fuses related to the ignition and starting circuit.
  • Replace with the correct amperage fuses as specified in the owner’s manual.

5. Ignition Switch Inspection

• Test Ignition Switch
  • Remove the steering column cover to access the ignition switch.
  • Use a multimeter to check for continuity when the key is turned to the start position.
  • Replace the ignition switch if there is no continuity.