how to fix P0171 code on my BMW 3 Series G20/G21 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal.
• Allow the engine to cool before starting work.

2. Inspect and Repair Air Intake System

1. Visual Inspection

   • Check all vacuum hoses connected to the intake manifold and air filter for cracks or disconnections.
   • Inspect gaskets and seals for damage.

2. Repair Leaks

   • Replace any damaged hoses or gaskets identified during inspection.

3. Clean or Replace MAF Sensor

1. Remove MAF Sensor

   • Disconnect the electrical connector and unscrew the MAF sensor from the air intake duct.

2. Clean MAF Sensor

   • Use MAF cleaner spray to carefully clean the sensor elements. Allow to dry completely.
   • If the MAF sensor is damaged, replace it with a new one.

4. Check Fuel Pressure

1. Connect Fuel Pressure Gauge

   • Locate the fuel rail test port, remove the cap, and connect the gauge.

2. Test Pressure

   • Turn the ignition on (without starting) and check the pressure reading. It should match the specifications for your model (typically between 50-60 psi).
   • If pressure is low, inspect the fuel pump and filter for issues.

5. Inspect Fuel Injectors

1. Remove Fuel Injectors

   • Disconnect the fuel rail and remove the injectors.

2. Test Injectors

   • Use a multimeter to check the resistance of each injector. Replace any injector that is out of specification.
   • Clean injectors if they are clogged using an ultrasonic cleaner or replace if necessary.

6. Check PCV System

1. Inspect PCV Valve

   • Remove and inspect the PCV valve for proper operation. Replace if it appears stuck or damaged.

2. Check Hoses

   • Ensure all hoses connected to the PCV system are in good condition and free of blockages.