my Toyota RAV4 XA50 (2019-2024) has a check engine light with code P0171, how to fix?

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, fuel pressure gauge, socket set, vacuum gauge.
• Disconnect the negative terminal of the battery to ensure safety.
• Allow the engine to cool before beginning work.

2. Inspect Air Intake System

• Remove the air intake duct connected to the throttle body.
• Visually inspect for cracks or loose clamps; replace any damaged parts.
• Reconnect the duct securely to ensure no air leaks.

3. Clean MAF Sensor

• Disconnect the MAF sensor electrical connector.
• Remove the MAF sensor using the appropriate socket.
• Clean the MAF sensor with MAF cleaner spray; do not touch the sensor element.
• Reinstall the MAF sensor and reconnect the electrical connector.

4. Test Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail test port.
• Turn the ignition to the "ON" position (do not start the engine) and check the pressure reading.
• Compare the reading against manufacturer specifications (typically 30-50 psi).
• If the pressure is low, inspect the fuel pump and filter for issues; replace if necessary.

5. Inspect Fuel Injectors

• Remove the fuel rail with the injectors attached.
• Check for clogs or dirt in the injectors; clean or replace as needed.
• Reinstall the fuel rail ensuring all seals are in good condition.

6. Check Vacuum Lines

• With the engine running, inspect all vacuum lines for hissing sounds or leaks.
• Use a vacuum gauge to check overall system integrity; replace any damaged lines.