how to fix the P0171 code on my BMW X3 G01 (2018-2024)?

Solution

1. Preparation

• Gather required tools and parts.
• Disconnect the negative terminal of the battery to avoid electrical shorts.

2. Inspect the Air Intake System

• Visually check all hoses and connections leading from the air filter to the intake manifold.
• Tighten any loose clamps and replace damaged hoses.
• Test for vacuum leaks using a smoke machine or by spraying carburetor cleaner around suspected areas and observing for RPM changes.

3. Check Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position without starting the engine and observe the pressure reading.
• Compare the reading to manufacturer specifications (typically between 50-60 psi for most BMW models).
• If pressure is low, inspect the fuel pump, fuel filter, and fuel lines for issues.

4. Clean or Replace the MAF Sensor

• Locate the MAF sensor in the air intake duct.
• Disconnect the electrical connector and remove the sensor.
• Clean the MAF sensor using an appropriate MAF cleaner, following the product instructions.
• If cleaning does not resolve the issue, replace the MAF sensor with a new one.

5. Inspect Oxygen Sensors

• Locate the upstream oxygen sensor (pre-catalytic converter).
• Check for any visible damage or corrosion on the connector.
• Use a multimeter to test the sensor's output voltage (should fluctuate between 0.1 to 0.9 volts).
• Replace any faulty oxygen sensors.

6. Inspect Fuel Injectors

• Remove the fuel rail to access the fuel injectors.
• Check for any signs of leaks or clogs.
• If needed, clean the injectors with a fuel injector cleaning solution, or replace them if they are faulty.