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

Solution

1. Preparation

• Gather tools and parts needed.
• Disconnect the battery to prevent electrical shorts.
• Ensure the vehicle is on a level surface and secure it with wheel chocks.

2. Inspect Air Intake System

• Sub-steps:
  1. Visually inspect all hoses for cracks or disconnections.
  2. Use a smoke machine to detect any vacuum leaks.
  3. Tighten any loose clamps or replace damaged hoses.
• Tools Required: Smoke machine, screwdriver set.
• Safety Warning: Allow engine to cool before inspecting components.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the MAF sensor connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Clean the sensor with MAF cleaner or replace if damaged.
  4. Reinstall the sensor and reconnect the connector.
• Tools Required: Torx screwdriver, MAF sensor cleaner.
• Safety Warning: Avoid touching the sensor element to prevent damage.

4. Check Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition on (do not start) and check for proper fuel pressure.
  3. If the pressure is low, inspect the fuel pump and filter.
• Tools Required: Fuel pressure gauge.
• Safety Warning: Fuel is flammable; work in a well-ventilated area.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail from the engine.
  2. Check each injector for clogs or leaks by performing a visual inspection.
  3. Clean or replace any faulty injectors as needed.
• Tools Required: Wrench set, injector cleaning kit.
• Safety Warning: Ensure fuel pressure is relieved before removing injectors.