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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety during repairs.

2. Inspect and Repair Vacuum Leaks

• Check all vacuum hoses connected to the intake manifold for cracks or disconnections.
• Use a smoke machine or spray carburetor cleaner around suspected areas; listen for changes in idle speed.
• Replace any damaged hoses or components found during inspection.

3. Clean or Replace MAF Sensor

• If the MAF sensor is dirty, remove it by unscrewing the mounting screws.
• Spray a dedicated MAF sensor cleaner onto the sensor element; do not touch it with fingers or tools.
• Allow it to dry completely before reinstalling.
• If the sensor is faulty, replace it with a new one.

4. Test and Repair Fuel System

• Connect a fuel pressure gauge to the fuel rail.
• Turn the key to the "On" position without starting the engine to check the pressure; it should meet manufacturer specifications.
• If pressure is low, check the fuel pump and fuel filter for proper operation.
• Replace the fuel filter if clogged, and consider replacing the fuel pump if it's not functioning properly.

5. Inspect and Clean Fuel Injectors

• Remove the fuel rail to access the injectors.
• Check for signs of clogging or leakage.
• Clean the injectors using a professional cleaning kit or replace them if they are defective.

6. Check Oxygen Sensors

• Inspect the wiring and connectors of the upstream oxygen sensor.
• If necessary, use a multimeter to test the sensor’s voltage output while the engine is running.
• Replace the oxygen sensor if it is not functioning correctly.