how to fix P0174 code in BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the working area is clean and well-ventilated.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a smoke machine or propane to detect leaks around the intake manifold and vacuum lines.
  3. Replace any damaged hoses or gaskets found during inspection.
• Tools Required: Smoke machine or propane torch, hose clamps, replacement hoses.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the MAF sensor connector.
  2. Remove the MAF sensor from the intake duct.
  3. If cleaning, use MAF sensor cleaner and a soft brush; let it dry completely before reinstallation.
  4. Reinstall the MAF sensor and reconnect the wiring.
• Tools Required: Torx screwdriver, MAF cleaner.

4. Inspect and Test Fuel System

• Sub-steps:
  1. Check the fuel pressure using a fuel pressure gauge; it should match manufacturer specifications (usually around 60-70 psi).
  2. If pressure is low, inspect the fuel pump and fuel filter for blockages or failures.
  3. Consider replacing any faulty fuel injectors if they are leaking or clogged.
• Tools Required: Fuel pressure gauge, socket set for fuel lines.

5. Inspect Oxygen Sensors

• Sub-steps:
  1. Check the wiring and connectors of the downstream oxygen sensor for damage.
  2. Test the sensor’s voltage output using a multimeter; replace if readings are outside expected ranges.
  3. If necessary, replace the oxygen sensor with a compatible part.
• Tools Required: Multimeter, O2 sensor socket.