how to fix P0171 lean code on Tesla Outback 4th Generation (2010-2014)?

Solution

1. Preparation

• Gather tools and safety equipment:
  • OBD-II scanner
  • Fuel pressure gauge
  • Multimeter
  • MAF sensor cleaner
  • Basic socket set
  • Safety glasses and gloves
• Ensure the vehicle is parked on a flat surface, and the engine is cool.

2. Inspect and Repair Vacuum Leaks

• Check all vacuum hoses attached to the intake manifold for cracks or damage.
• If a leak is found, replace the damaged hose.
• Use smoke testing if necessary to detect hard-to-find leaks.

3. Clean or Replace MAF Sensor

• Locate the MAF sensor in the air intake duct.
• Disconnect the electrical connector and unscrew the sensor.
• Clean the MAF sensor with MAF cleaner and let it dry completely.
• Reinstall the sensor and reconnect the electrical connector.

4. Check and Adjust Fuel Pressure

• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position without starting the engine to check the fuel pressure.
• Compare the reading with manufacturer specifications (typically 50-60 psi for Subaru).
• If pressure is low, consider replacing the fuel pump or checking the fuel filter.

5. Inspect and Test Fuel Injectors

• Listen for the clicking sound of fuel injectors using a stethoscope or mechanic's stethoscope.
• If any injectors are silent, consider replacing them.
• Check for fuel leaks around the injectors and replace O-rings if necessary.

6. Verify ECT Sensor Functionality

• Disconnect the ECT sensor and measure resistance with a multimeter.
• Compare readings to manufacturer specifications for temperature.
• Replace the ECT sensor if readings are out of range.