how to fix P0171 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.
• Allow the engine to cool before beginning work.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect the air intake hoses and connections for any cracks or loose fittings.
  2. Use a smoke machine to identify any vacuum leaks in the intake manifold or hoses.
  3. If leaks are found, replace damaged hoses or reseal connections as necessary.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Remove the MAF sensor from the air intake duct.
  2. Use MAF sensor cleaner to spray and clean the sensing element. Avoid touching it directly with tools or fingers.
  3. Reinstall the MAF sensor and ensure all connections are secure.
  4. If the sensor is damaged, replace it with a new one.

4. Check Fuel Pressure

• Sub-steps:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Attach the fuel pressure gauge and turn the ignition to the "ON" position without starting the engine.
  3. Record the fuel pressure reading, which should typically be between 43-50 psi for a RAV4.
  4. If pressure is low, inspect the fuel pump and replace if necessary.

5. Inspect and Clean Fuel Injectors

• Sub-steps:
  1. Remove the fuel injectors from the fuel rail.
  2. Use an ultrasonic cleaner or injector cleaning kit to clean the injectors.
  3. Test injectors for proper spray pattern and flow.
  4. Replace any faulty injectors with new ones.

6. Test Oxygen Sensors

• Sub-steps:
  1. Inspect the wiring and connectors of the upstream oxygen sensor for damage.
  2. Use a multimeter to test the voltage output of the oxygen sensor; it should fluctuate between 0.1 to 0.9 volts.
  3. If the sensor is faulty, replace it with a new one.