my BMW X5 F15 (2014-2019) check engine light codes P0171 and P0174

Solution

1. Preparation

• Gather required tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to ensure safety throughout the repair process.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to identify any hidden leaks.
  • Replace any damaged hoses or gaskets identified during inspection.
• Tools Required: Smoke machine, carburetor cleaner, pliers.
• Safety Warnings: Ensure the engine is cool and do not smoke near flammable materials.

3. Clean or Replace MAF Sensor

• Sub-steps:
  • Locate the MAF sensor in the air intake duct.
  • Carefully disconnect the electrical connector.
  • Remove the MAF sensor using a Torx or Phillips screwdriver.
  • Clean the sensor with MAF cleaner or replace it if damaged.
  • Reinstall the MAF sensor and reconnect the electrical connector.
• Tools Required: Torx/Phillips screwdriver, MAF cleaner.
• Safety Warnings: Handle the sensor carefully to avoid damage.

4. Check Fuel Pressure

• Sub-steps:
  • Locate the fuel pressure test port on the fuel rail.
  • Connect the fuel pressure gauge to the test port.
  • Turn the ignition to the "ON" position (do not start the engine) to check pressure readings.
  • If the pressure is below specifications (check service manual for exact values), inspect the fuel pump and fuel filter.
• Tools Required: Fuel pressure gauge.
• Safety Warnings: Relieve fuel system pressure before disconnecting any components.

5. Inspect Throttle Body

• Sub-steps:
  • Remove the intake duct connected to the throttle body.
  • Inspect the throttle body for carbon buildup and clean it using throttle body cleaner if necessary.
  • Reattach the intake duct ensuring a proper seal.
• Tools Required: Throttle body cleaner, screwdriver.
• Safety Warnings: Ensure the battery is disconnected before working on electrical components.