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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent any electrical shorts.
• Allow the engine to cool before working on it.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps
• Inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
• Replace any damaged hoses and ensure all connections are tight.

3. Clean or Replace the MAF Sensor

• Tools Required: MAF cleaner, screwdriver
• Remove the MAF sensor from the air intake duct using a screwdriver.
• Clean the sensor with MAF cleaner and let it dry completely; if damaged, replace it with a new sensor.

4. Test and Repair Fuel System

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail and turn the ignition on (do not start the engine).
• Verify that the fuel pressure is within specifications (usually around 40-50 PSI for most vehicles).
• If low, check the fuel pump, fuel filter, and fuel injectors for blockages or failures. Replace components as necessary.

5. Inspect Oxygen Sensors

• Tools Required: O2 sensor socket
• Locate the upstream oxygen sensor and disconnect its connector.
• Test the voltage output of the sensor using a multimeter (should fluctuate during engine operation).
• If the sensor is faulty or not functioning properly, replace it.