how to fix P0171 lean code in Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety during repairs.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum lines for cracks, wear, or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect leaks while the engine is running.
  3. Replace any damaged vacuum hoses.

Tools Required:

• Smoke machine (optional)
• Carburetor cleaner

3. Fuel System Inspection

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the ON position (without starting) to check for proper fuel pressure.
  3. If pressure is low, check the fuel pump and filter for proper operation; replace if necessary.

Tools Required:

• Fuel pressure gauge

4. MAF Sensor Maintenance

• Sub-steps:
  1. Disconnect the MAF sensor connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Clean the MAF sensor with MAF sensor cleaner and let it dry before reinstallation.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

Tools Required:

• MAF sensor cleaner

5. Oxygen Sensor Check

• Sub-steps:
  1. Locate the upstream oxygen sensor in the exhaust system.
  2. Disconnect the sensor and inspect the wiring for damage.
  3. Use a multimeter to check the sensor's voltage output; replace if it is out of specification.

Tools Required:

• Multimeter

6. Fuel Injector Cleaning/Replacement

• Sub-steps:
  1. Remove the fuel rail to access the fuel injectors.
  2. Inspect each injector for clogs or leaks; clean using an ultrasonic cleaner or replace if damaged.
  3. Reinstall the fuel rail and reattach necessary components.

Tools Required:

• Ultrasonic cleaner (optional)