how to diagnose P0171 code on Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses and intake manifold for cracks or loose connections.
  • Use a smoke machine to detect leaks in the intake system.
  • Replace any damaged hoses or re-secure loose connections.

3. Check and Clean MAF Sensor

• Tools Required: MAF sensor cleaner
• Sub-steps:
  • Locate the MAF sensor in the air intake system.
  • Disconnect the electrical connector and remove the MAF sensor.
  • Spray the MAF sensor with MAF cleaner and allow it to dry completely before reinstalling.

4. Test Fuel Pressure

• Tools Required: Fuel pressure gauge
• Sub-steps:
  • Connect the fuel pressure gauge to the fuel rail test port.
  • Turn the ignition to the "On" position (do not start the engine) and record the pressure.
  • Compare the reading to the specifications in the service manual (typically around 50-60 psi).
  • If pressure is low, check for clogged fuel filter or failing fuel pump and replace as needed.

5. Inspect Fuel Injectors

• Sub-steps:
  • Remove the fuel rail with injectors attached.
  • Visually inspect for any signs of leaks or damage.
  • Test each injector for proper operation using a multimeter or injector tester.
  • Clean or replace injectors if faulty.