what does it mean if my Toyota Highlander XU70 (2020-Present) has a P0171 code?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety.
• Allow the engine to cool before starting the work.

2. Inspect for Vacuum Leaks

• Use a smoke machine or carburetor cleaner to identify any vacuum leaks in the intake system.
• Replace any damaged or leaking hoses or gaskets.

3. Check Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (do not start the engine) and check the fuel pressure reading.
• If pressure is below specifications (typically around 50-60 psi for most engines), inspect the fuel pump and filter.

4. Clean or Replace MAF Sensor

• Disconnect the MAF sensor electrical connector.
• Remove the MAF sensor from the intake duct.
• Clean the sensor with MAF cleaner spray, allowing it to dry completely.
• Reinstall the sensor and reconnect the electrical connector.

5. Inspect Fuel Injectors

• Remove the fuel rail to access the fuel injectors.
• Inspect each injector for clogs or leaks.
• Clean or replace any faulty injectors as necessary.

6. Replace Oxygen Sensors (if needed)

• If diagnostic checks indicate a malfunctioning oxygen sensor, locate the sensor (upstream or downstream).
• Remove the sensor using an oxygen sensor socket.
• Install the new sensor and reconnect the wiring harness.