how to solve the P0171 code on my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

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

Tools Required:

• OBD-II scanner
• Vacuum gauge
• Fuel pressure gauge
• Socket set
• Screwdrivers
• Cleaning solvent (e.g., MAF cleaner)

2. Inspect Air Intake System

• Remove the air intake duct and inspect for cracks or loose connections.
• Check the intake manifold gasket for signs of wear or leaks.
• Use a vacuum gauge to test for leaks; a reading outside of the normal range indicates a leak.

3. Clean the MAF Sensor

• Remove the MAF sensor from the air intake system.
• Spray MAF cleaner onto the sensor to remove dirt and deposits. Let it dry completely before reinstallation.

4. Check Fuel Pressure

• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition key to the "ON" position (without starting the engine) to read the pressure. Compare the reading with the manufacturer's specifications.
• If the pressure is low, inspect the fuel pump and fuel filter for issues.

5. Inspect and Test Fuel Injectors

• Remove the fuel injector connectors and inspect for corrosion.
• Perform a resistance test on each injector with a multimeter to ensure they are within specifications.
• Use a cleaning solvent to clear any blockages if necessary.

6. Reconnect and Test

• Reconnect all components and the battery.
• Clear the error codes using the OBD-II scanner.
• Start the engine and observe for any returning codes or symptoms.