how to fix P0171 code in Toyota RAV4 Fourth Generation (2013-2018)

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the battery to ensure safety.
• Allow the engine to cool down before beginning work.

2. Inspect and Repair Air Intake System

• Sub-steps:
  • Remove the air intake duct to access the MAF sensor.
  • Inspect all hoses for cracks and leaks, particularly around the intake manifold.
  • Replace any damaged vacuum hoses.
  • Reinstall the air intake duct securely.

3. Clean or Replace Mass Air Flow Sensor

• Sub-steps:
  • Disconnect the MAF sensor connector.
  • Remove the MAF sensor from the intake.
  • Clean the sensor with MAF cleaner spray (do not touch the sensor element).
  • If cleaning does not resolve the issue, replace the MAF sensor with a new unit.
  • Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel System

• Sub-steps:
  • Connect a fuel pressure gauge to the fuel rail.
  • Turn the ignition to the "ON" position (do not start the engine) to check fuel pressure.
  • Compare the reading with the manufacturer's specifications (typically between 50-60 psi).
  • If pressure is low, replace the fuel pump or filter as necessary.
  • Ensure all fuel injectors are clean and functioning; replace if necessary.

5. Inspect Oxygen Sensors

• Sub-steps:
  • Check the wiring and connectors of the upstream oxygen sensor for damage.
  • Use a multimeter to test the oxygen sensor's voltage output.
  • Replace the sensor if it is not functioning properly.