my BMW 3 Series E90/E91 (2005-2012) has a P0171 code how do I fix it

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery before starting work on electrical components.

2. Inspect and Repair Air Intake System

• Tools Required: Screwdriver set, vacuum gauge.
• Check all air intake hoses for cracks or leaks. Replace any damaged hoses.
• Tighten any loose clamps and ensure a proper seal.

3. Clean the Mass Airflow Sensor (MAF)

• Tools Required: MAF cleaner, soft brush.
• Remove the MAF sensor from the air intake duct.
• Spray MAF cleaner onto the sensor element and allow it to dry completely before reinstalling.

4. Check and Replace Fuel Filter (if necessary)

• Tools Required: Wrench set, fuel line disconnect tool.
• Locate the fuel filter and disconnect the fuel lines using the disconnect tool.
• Replace the fuel filter with a new one, ensuring proper orientation and tight connections.

5. Inspect and Test Fuel Injectors

• Tools Required: Fuel injector cleaning kit, multimeter.
• Remove the fuel rail to access the injectors.
• Test each injector with the multimeter for resistance.
• Clean the injectors using the cleaning kit or replace if faulty.

6. Reassemble and Reset the System

• Reinstall any components removed during the inspection.
• Reconnect the battery.
• Use the OBD-II scanner to clear the P0171 code and reset the system.