how to fix P0171 code on Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety.

Tools Required:

• OBD-II scanner
• Fuel pressure gauge
• Torque wrench
• Socket set
• Screwdrivers
• MAF cleaner

2. Inspect and Repair Air Intake System

• Sub-step 1: Visually inspect the air intake duct for cracks or loose fittings. Repair or replace as needed.
• Sub-step 2: Check the air filter; replace if dirty or clogged.
• Sub-step 3: Reassemble the intake system ensuring all connections are tight.

3. Clean or Replace MAF Sensor

• Sub-step 1: Disconnect the MAF sensor connector.
• Sub-step 2: Remove the MAF sensor from the intake tract.
• Sub-step 3: Clean the sensor using MAF cleaner. Do not touch the sensor element.
• Sub-step 4: Reinstall the MAF sensor and reconnect the electrical connector.

4. Check and Adjust Fuel Pressure

• Sub-step 1: Connect the fuel pressure gauge to the fuel rail test port.
• Sub-step 2: Turn the ignition to the "On" position (do not start) to check the pressure reading.
• Sub-step 3: If pressure is low, inspect the fuel pump and fuel filter; replace if necessary.

5. Inspect Fuel Injectors

• Sub-step 1: Remove the fuel rail to access the injectors.
• Sub-step 2: Inspect for clogs; clean or replace the injectors as needed.
• Sub-step 3: Reinstall the fuel rail and ensure injectors are seated properly.

6. Verify Vacuum Leaks

• Sub-step 1: Use a smoke machine or carburetor cleaner around vacuum hoses and gaskets to detect leaks.
• Sub-step 2: Repair any leaks found by replacing damaged hoses or gaskets.