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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid electrical shorts while working on the vehicle.

2. Inspect and Repair Intake System

• Sub-steps:
  1. Visually inspect all hoses connected to the air intake system for cracks or disconnections.
  2. Replace any damaged hoses with OEM parts.
  3. Reconnect all intake components securely.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the sensor from the duct.
  3. Clean the MAF sensor with MAF cleaner spray; do not touch the sensor element.
  4. If cleaning does not resolve the issue, replace the MAF sensor with a new OEM part.

4. Check and Repair Fuel Delivery System

• Sub-steps:
  1. Verify fuel pressure using a fuel pressure gauge; compare readings with manufacturer specifications.
  2. If pressure is low, check the fuel pump and filter; replace as necessary.
  3. Inspect the fuel pressure regulator for proper function; replace if faulty.

5. Inspect Oxygen Sensors

• Sub-steps:
  1. Locate the upstream oxygen sensor (pre-catalytic converter).
  2. Check for any damage to the sensor wiring or connector.
  3. If issues are found, replace the oxygen sensor with an OEM part.

6. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery and clear the stored P0171 code using an OBD-II scanner.
  2. Take the vehicle for a test drive to ensure that the code does not reappear.

Tools Required:

• OBD-II scanner
• Screwdrivers (flathead and Phillips)
• Socket set
• Fuel pressure gauge
• MAF cleaner spray

Parts Required:

• Vacuum hoses (as needed)
• Mass Air Flow sensor (if applicable)
• Fuel filter (if applicable)
• Oxygen sensor (if applicable)

Estimated Repair Time: 2-4 hours

Safety Warnings:

• Disconnect the battery before working on electrical components.
• Allow the engine to cool before inspecting or working on the intake or fuel system.