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

Solution

1. Preparation

• Gather tools: OBD-II scanner, multimeter, vacuum gauge, fuel pressure gauge, basic hand tools (sockets, wrenches).
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect Air Intake System

• Remove the air intake duct connected to the throttle body.
• Check for any visible cracks or loose connections in the hoses.
• Use a vacuum gauge to check for leaks; if present, replace the damaged hoses.

3. Clean or Replace MAF Sensor

• Disconnect the electrical connector from the MAF sensor.
• Remove the MAF sensor from the air intake.
• Clean the sensor with MAF cleaner spray; avoid touching the sensor with fingers.
• Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel System

• Attach the fuel pressure gauge to the fuel rail’s service port.
• Turn the ignition key to the "ON" position (do not start the engine) and check the fuel pressure reading; it should match the specifications in the service manual (typically 30-50 psi for RAV4).
• If the pressure is low, check the fuel filter and replace it if necessary.

5. Inspect Fuel Injectors

• Remove the fuel rail from the engine (ensure to relieve fuel pressure first).
• Visually inspect the fuel injectors for clogs or leaks.
• Clean or replace any faulty injectors.

6. Reassemble and Test

• Reinstall the intake duct and ensure all connections are secure.
• Reconnect the negative battery terminal.
• Start the engine and monitor for any abnormal sounds or leaks.