my BMW 5 Series F10/F11 (2010-2017) has a check engine light and code P0171

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety.
• Allow the engine to cool before working on any components.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Hose clamps, screwdriver, vacuum pump.
• Steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a vacuum pump to check for leaks in the intake manifold.
  3. Replace any damaged hoses or gaskets as necessary.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, small screwdriver.
• Steps:
  1. Locate the MAF sensor on the air intake duct.
  2. Disconnect the electrical connector and unscrew the sensor from its housing.
  3. Clean the sensor elements with MAF sensor cleaner and let it dry.
  4. Reinstall the sensor and reconnect the electrical connector.

4. Check and Adjust Fuel Pressure

• Tools Required: Fuel pressure gauge, wrench.
• Steps:
  1. Locate the fuel rail and connect the fuel pressure gauge.
  2. Turn the ignition key to the "ON" position without starting the engine to check pressure readings.
  3. Compare the reading with manufacturer specifications (usually around 50-60 psi for BMW).
  4. If pressure is low, inspect the fuel pump and filters for issues; replace as necessary.

5. Inspect and Test Fuel Injectors

• Tools Required: Fuel injector cleaner, multimeter.
• Steps:
  1. Disconnect the fuel injector connectors and test with a multimeter for resistance.
  2. If injectors are faulty (no continuity or out of range), replace them.
  3. Use a fuel injector cleaner to clean if they are clogged, following the cleaner's instructions.