how to fix P0174 fuel trim system lean bank 2 in BMW 5 Series G30/G31 (2017-2024)?

Solution

1. Preparation

• Gather tools and ensure the vehicle is parked on a flat surface.
• Disconnect the negative terminal of the battery to eliminate electrical hazards.

Tools Required:

• OBD-II scanner
• Fuel pressure gauge
• Multimeter
• Socket set
• Torque wrench

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold.
  2. Use a smoke machine or carburetor cleaner to identify any leaks; apply around suspected areas and watch for changes in engine RPM.
  3. Replace any damaged hoses or gaskets.

3. Check and Clean MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the intake air duct.
  2. Disconnect the electrical connector and remove the sensor using the appropriate socket.
  3. Clean the sensor with MAF cleaner spray and let it dry before reinstalling.
  4. Reconnect the sensor and ensure it is secured properly.

4. Test and Repair Fuel System

• Sub-steps:
  1. Attach the fuel pressure gauge to the fuel rail and turn the ignition to the "On" position without starting the engine.
  2. Check the fuel pressure reading against manufacturer specifications (usually 50-60 psi for BMW).
  3. If pressure is low, check for clogged fuel filters or a failing fuel pump. Replace any faulty components.
  4. Inspect fuel injectors; if clogs are found, remove and clean or replace as necessary.

5. Oxygen Sensor Testing

• Sub-steps:
  1. Locate the oxygen sensors upstream and downstream of bank 2.
  2. Disconnect the electrical connectors and check the voltage output using a multimeter while the engine is running.
  3. Replace any faulty oxygen sensors showing incorrect voltage readings.