how to fix the P0171 code on my BMW 3 Series F30/F31 (2012-2019)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect the air filter and replace if dirty.
  2. Check all intake hoses for cracks or loose connections; tighten or replace as necessary.
  3. Clean the MAF sensor using MAF sensor cleaner. Allow it to dry before reinstallation.

3. Check and Adjust Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition on (do not start) and read the fuel pressure. It should be within the manufacturer’s specifications (generally around 50-60 psi for BMW).
  3. If low, check the fuel pump operation and fuel filter condition. Replace as necessary.

4. Inspect and Replace Vacuum Lines

• Sub-steps:
  1. Visually inspect all vacuum lines for wear or damage.
  2. Replace any that appear cracked or compromised.

5. Test and Replace Oxygen Sensors (if necessary)

• Sub-steps:
  1. Use a multimeter to check the voltage output of the oxygen sensors.
  2. If the readings are outside the normal range (0.1-0.9 volts for most sensors), replace the faulty sensor.