how to fix P0171 and P0174 codes in my BMW 5 Series F10/F11 (2010-2017)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Vacuum Hoses

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks, wear, or disconnections.
  2. Replace any damaged hoses with OEM parts.
  3. Reconnect all hoses securely and ensure they are routed correctly.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the intake system.
  2. Disconnect the electrical connector.
  3. Remove the MAF sensor from its housing (usually requires a Torx screwdriver).
  4. Clean the sensor with MAF cleaner spray; avoid touching the sensor element.
  5. If the sensor is damaged, replace it with a new one.
  6. Reinstall the MAF sensor and reconnect the electrical connector.

4. Check and Replace Fuel Filter (If Necessary)

• Sub-steps:
  1. Locate the fuel filter in the fuel line.
  2. Relieve fuel pressure by removing the fuel pump fuse and running the engine until it stalls.
  3. Disconnect the fuel lines from the filter using a fuel line disconnect tool.
  4. Replace the fuel filter with a new one, ensuring correct flow direction.
  5. Reconnect the fuel lines and reinsert the fuel pump fuse.

5. Verify Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition to the "On" position without starting the engine and check the pressure.
  3. Compare the reading with the manufacturer’s specifications (typically around 50-60 psi).
  4. If pressure is low, consider checking the fuel pump and regulator.

6. Inspect Injectors

• Sub-steps:
  1. Remove the engine cover to access the fuel injectors.
  2. Inspect the wiring and connectors for damage.
  3. Perform a bench test on each injector to ensure proper operation and spray pattern.
  4. Replace any faulty injectors with OEM replacements.