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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the vehicle is on a flat surface, and raise it using jack stands if necessary.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to check for leaks around the intake manifold gaskets.
  • Replace any damaged hoses or gaskets as necessary.

3. Clean or Replace MAF Sensor

• Sub-steps:
  • Locate the MAF sensor in the air intake system.
  • Disconnect the electrical connector and unscrew the sensor from the housing.
  • Clean the MAF sensor with MAF cleaner spray.
  • Allow it to dry completely, then reinstall it. If damaged, replace it with a new sensor.

4. Check and Adjust Fuel Pressure

• Sub-steps:
  • Connect a fuel pressure gauge to the fuel rail test port.
  • Turn the ignition to the "ON" position (do not start) to check fuel pressure.
  • Compare the reading to manufacturer specifications (typically 50-60 psi for Subaru).
  • If pressure is low, inspect the fuel pump and fuel filter for issues and replace as necessary.

5. Inspect and Clean Fuel Injectors

• Sub-steps:
  • Remove the fuel rail and access the fuel injectors.
  • Visually inspect each injector for clogs or leaks.
  • Use an injector cleaning kit to clean injectors if necessary, or replace them if faulty.

6. Test Oxygen Sensors

• Sub-steps:
  • Locate the upstream oxygen sensor (pre-catalytic converter).
  • Use a multimeter to measure voltage output while the engine is running.
  • If readings are out of specification (typically oscillating between 0.1V and 0.9V), replace the oxygen sensor.