how to fix the P0171 code in my BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all hoses and connections in the air intake system for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to identify leaks while the engine is running.
  • Replace any damaged hoses or gaskets found during the inspection.

3. Clean MAF Sensor

• Tools Required: MAF sensor cleaner
• Sub-steps:
  • Locate the MAF sensor, typically situated between the air filter and throttle body.
  • Disconnect the electrical connector and the intake pipe from the MAF sensor.
  • Spray the MAF sensor with MAF cleaner, allowing it to dry completely before reinstalling.
  • Reconnect the intake pipe and electrical connector.

4. Check and Repair Fuel System

• Sub-steps:
  • Test the fuel pressure using a fuel pressure gauge at the fuel rail; compare the reading with manufacturer specifications.
  • If fuel pressure is low, inspect the fuel pump and replace if necessary.
  • Replace the fuel filter if it is clogged or due for replacement.
  • Inspect and clean fuel injectors if they are suspected to be clogged.

5. Inspect Oxygen Sensors

• Sub-steps:
  • Locate the upstream and downstream oxygen sensors.
  • Use a multimeter to check the voltage output from the sensors; compare against manufacturer specifications.
  • Replace any faulty oxygen sensors.

6. Throttle Body Inspection

• Sub-steps:
  • Remove the throttle body assembly, if necessary, for cleaning.
  • Clean the throttle body with an appropriate cleaner to remove carbon buildup.
  • Reinstall the throttle body and ensure all connections are secure.