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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid any electrical shorts.

Tools Required:

• OBD-II scanner
• Fuel pressure gauge
• Multimeter
• Socket set
• Cleaning supplies (MAF cleaner, etc.)

2. Inspect and Repair Air Intake System

• Air Filter: Check and replace if dirty.
• Vacuum Hoses: Inspect all vacuum hoses for cracks or leaks. Replace any damaged hoses.
• Intake Manifold: Remove the intake manifold if necessary to inspect for leaks. Use a smoke machine for thorough testing.

3. Clean or Replace MAF Sensor

• Disconnect the electrical connector from the MAF sensor.
• Remove the MAF sensor from the intake.
• Clean the sensor with MAF cleaner. Allow it to dry completely before reinstalling.
• If cleaning does not resolve the issue, replace the MAF sensor.

4. Check Fuel System

• Fuel Pressure: Connect the fuel pressure gauge to the fuel rail. Start the engine and check that the pressure matches the manufacturer's specifications (typically between 50-60 psi).
• If pressure is low, inspect the fuel pump and fuel filter for clogs. Replace if necessary.

5. Inspect Fuel Injectors

• Check for leaks around the injectors.
• If injectors are clogged, remove and clean them using an ultrasonic cleaner or replace them if necessary.

6. Reconnect and Reset

• Reconnect the battery.
• Clear the P0171 code with the OBD-II scanner.
• Start the engine and check for any reoccurring codes.