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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Repair Air Intake System

• Inspect for Leaks:
  • Visually inspect all hoses and connections for cracks or disconnections.
  • Use a smoke machine if available to detect vacuum leaks.
• Tighten or Replace Hoses:
  • Tighten any loose clamps or connections.
  • Replace any damaged hoses.

3. Clean the MAF Sensor

• Remove the MAF Sensor:
  • Locate the MAF sensor in the air intake duct.
  • Disconnect the electrical connector and remove the mounting screws.
• Clean the Sensor:
  • Use MAF sensor cleaner (do not use throttle body cleaner).
  • Spray the cleaner on the sensor element and let it dry completely before reinstalling.

4. Check and Adjust Fuel Pressure

• Connect Fuel Pressure Gauge:
  • Locate the fuel rail and connect the gauge to the service port.
• Start the Engine:
  • Observe the fuel pressure reading; compare it to the manufacturer's specifications.
  • If the pressure is low, proceed to check the fuel pump and filter for issues.

5. Inspect and Clean Fuel Injectors

• Remove Fuel Injectors:
  • Relieve fuel pressure and disconnect the fuel lines.
  • Remove the intake manifold if necessary to access the injectors.
• Clean Injectors:
  • Use a professional fuel injector cleaning kit or replace injectors if they are clogged or malfunctioning.

6. Verify Engine Coolant Temperature Sensor

• Check Operation:
  • Using a multimeter, verify the resistance of the sensor at different temperatures.
  • Replace if out of specification.

7. Verify PCV Valve

• Inspect Functionality:
  • Remove the PCV valve from the intake manifold.
  • Shake it; a rattling sound indicates it is functioning; replace if not.