my BMW 5 Series G30/G31 (2017-2024) has a check engine light with code P0171, what does it mean?

Solution

1. Preparation

• Tools Required: OBD-II scanner, vacuum gauge, fuel pressure gauge, socket set, screwdrivers, cleaning solvent.
• Disconnect the battery to ensure safety while working on electrical components.
• Allow the engine to cool down if previously running.

2. Inspect Air Intake System

• Remove the air intake duct and inspect for cracks or gaps.
• Replace any damaged hoses or connections.
• Reinstall the air intake duct ensuring a secure fit.

3. Clean or Replace MAF Sensor

• Gently remove the MAF sensor from the air intake.
• Clean the sensor using MAF cleaner spray; do not touch the sensing element.
• If the sensor is faulty, replace it with a new one, ensuring proper orientation during installation.

4. Check Fuel Pressure

• Connect the fuel pressure gauge to the fuel rail service port.
• Start the engine and monitor the fuel pressure; it should match the specifications in the service manual (typically around 50-60 psi for most models).
• If the pressure is low, inspect the fuel pump and filter for issues, replacing them if necessary.

5. Inspect and Test Fuel Injectors

• Remove the fuel injectors from the engine.
• Check for clogs; clean or replace injectors as needed.
• Ensure the injector seals are intact and replace if damaged before reinstallation.

6. Reassemble and Reset Codes

• Reinstall any components removed during the inspection.
• Reconnect the battery.
• Use the OBD-II scanner to clear the P0171 code.
• Start the engine and allow it to run for a few minutes to ensure proper operation.