how do I fix the P0171/P0174 codes on my BMW X5 G05 (2019-2024)?

Solution

1. Preparation

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

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect leaks by applying it along hoses and gaskets while the engine is running.
  3. Replace any damaged hoses or gaskets identified during inspection.

3. Clean or Replace the MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor on the air intake tube.
  2. Disconnect the electrical connector and remove the sensor from the housing.
  3. Clean the MAF sensor with MAF cleaner spray (do not use other cleaners).
  4. Allow the sensor to dry completely before reinstalling.
  5. If damaged or excessively dirty, replace the MAF sensor.

4. Check Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition to the "ON" position (do not start the engine) and check the pressure reading against specifications (typically around 50-60 psi).
  3. If pressure is low, check the fuel pump operation and fuel filter for clogs and replace as necessary.

5. Inspect and Clean Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail with injectors attached (ensure fuel pressure is relieved beforehand).
  2. Inspect the injectors for clogs and clean them with an appropriate injector cleaner.
  3. If any injector is faulty, replace it with a new one.

6. Examine the PCV System

• Sub-steps:
  1. Locate the PCV valve and hoses.
  2. Remove and inspect the PCV valve for blockages or wear.
  3. Replace if necessary and ensure all connections are secure.