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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before working on it.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Inspect all hoses connected to the intake manifold for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to identify leaks if necessary.
  3. Replace any damaged hoses or gaskets.
• Tools Required: Smoke machine, carburetor cleaner, hose clamp pliers

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the MAF sensor connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Use MAF sensor cleaner to spray and clean the sensor element.
  4. Allow it to dry completely and reinstall the sensor.
• Tools Required: Torx screwdriver, MAF sensor cleaner

4. Check Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "ON" position without starting the engine to check fuel pressure.
  3. Compare the reading to manufacturer specifications; replace the fuel filter if pressure is low.
  4. If pressure is adequate, inspect the fuel injectors for clogs or malfunctions.
• Tools Required: Fuel pressure gauge, socket set

5. Inspect and Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream oxygen sensor (before the catalytic converter).
  2. Use a multimeter to test the sensor’s voltage output while the engine is running.
  3. Replace the sensor if the readings do not match manufacturer specifications.
• Tools Required: Multimeter, oxygen sensor socket