how to fix the P0171 code on my BMW 3 Series G20/G21 (2019-2024)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Repair Air Intake System

• Tools Required: Screwdriver set, flashlight
• Sub-steps:
  1. Visually inspect the air intake duct for cracks or loose connections.
  2. Tighten or replace any loose or damaged components (e.g., hose clamps).
  3. Check the air filter and replace if it is dirty or clogged.

3. Clean Mass Airflow Sensor

• Tools Required: MAF cleaner spray, lint-free cloth
• Sub-steps:
  1. Locate the MAF sensor in the air intake path.
  2. Disconnect the electrical connector and remove the MAF sensor.
  3. Spray MAF cleaner on the sensing element and allow it to dry completely before reinstalling.

4. Test and Replace Fuel Components

• Tools Required: Fuel pressure gauge, socket set
• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail test port.
  2. Turn on the ignition (without starting) to check fuel pressure.
  3. If pressure is below specifications, inspect the fuel pump and filter.
  4. Replace the fuel filter if necessary and consider replacing the fuel pump if it is faulty.

5. Inspect and Clean Fuel Injectors

• Tools Required: Injector cleaner or ultrasonic cleaner, socket set
• Sub-steps:
  1. Remove fuel injectors from the engine.
  2. Clean injectors using a professional injector cleaner or ultrasonic cleaner.
  3. Reinstall cleaned or new injectors ensuring proper sealing.

6. Check and Repair Vacuum Lines

• Tools Required: Visual inspection tools
• Sub-steps:
  1. Locate and visually inspect all vacuum lines connected to the intake manifold.
  2. Replace any cracked or disconnected vacuum hoses.
  3. Ensure all connections are tight and secure.