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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery cable to ensure safety.

2. Inspect and Repair the Air Intake System

• Tools Required: Hose clamps, screwdriver, flashlight.
• Check all hoses and connections in the air intake for cracks or loose fittings.
• Tighten any loose clamps and replace any damaged hoses.
• If a leak is found, replace the defective part.

3. Clean or Replace the MAF Sensor

• Tools Required: MAF sensor cleaner.
• Remove the MAF sensor from the air intake.
• Spray the MAF sensor with the cleaner, avoiding touching the sensor elements.
• Allow it to dry completely before reinstalling.

4. Check Fuel System Pressure

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail.
• Start the engine and check that the fuel pressure is within the manufacturer's specified range (typically around 40-50 psi).
• If pressure is low, inspect the fuel pump and fuel filter for issues.

5. Inspect Fuel Injectors

• Tools Required: O-ring replacements, fuel injector cleaner.
• Remove the fuel injectors from the engine.
• Check for clogged injectors and replace or clean them as necessary.
• Reinstall injectors with new O-rings to prevent leaks.

6. Check Engine Vacuum Leaks

• Tools Required: Vacuum gauge, hose.
• Connect the vacuum gauge to the intake manifold.
• Start the engine and observe the vacuum reading; it should be within the normal range (typically 18-22 inHg).
• If vacuum is low, inspect for leaks in vacuum hoses and the intake manifold.