how can I fix the P0171 code in my Toyota Highlander Third Generation (2014-2019)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Repair Air Intake System

• Tools Required: Screwdriver set, flashlight
• Steps:
  1. Open the hood and visually inspect air intake hoses for cracks or loose connections.
  2. Tighten any loose clamps or replace damaged hoses as needed.
  3. Check the air filter and replace if clogged.

3. Clean MAF Sensor

• Tools Required: MAF sensor cleaner
• Steps:
  1. Disconnect the MAF sensor's electrical connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Spray the MAF sensor with the cleaner and allow it to dry completely before reinstalling.

4. Test Fuel Pressure

• Tools Required: Fuel pressure gauge
• Steps:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Attach the fuel pressure gauge and turn the ignition to the "ON" position without starting the engine.
  3. Check that the fuel pressure meets the manufacturer's specifications (typically around 35-45 psi).
  4. If pressure is low, check the fuel pump and fuel filter for issues.

5. Inspect Fuel Injectors

• Tools Required: Fuel injector cleaning kit (if necessary)
• Steps:
  1. Remove the fuel rail to access the fuel injectors.
  2. Inspect each injector for clogs or leaks.
  3. If clogs are found, use a fuel injector cleaning kit to clean them or replace as necessary.

6. Address Exhaust Leaks

• Tools Required: Exhaust leak detection tool or soapy water
• Steps:
  1. Visually inspect exhaust manifold and connections for cracks or leaks.
  2. Use soapy water to check for leaks; bubbles will form at the leak site.
  3. Seal any leaks with appropriate exhaust sealant or replace damaged components.