how to fix P0171 code in Toyota Tacoma N300 (2016-Present)

Solution

1. Preparation

• Gather all tools and parts needed for the repair.
• Disconnect the negative battery cable to ensure safety while working on electrical components.
• Allow the engine to cool before proceeding.

2. Inspect and Repair Air Intake System

• Tools Required: Socket set, screwdrivers, vacuum gauge
• Inspect all hoses and connections in the air intake system for cracks or loose fittings.
• Tighten any loose clamps and replace damaged hoses.
• If an air leak is found, replace the defective components.

3. Fuel Pressure Check and Adjustment

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (do not start the engine) and observe the pressure reading.
• Compare the reading to the manufacturer specifications (typically between 43-50 psi for the Tacoma).
• If the pressure is low, inspect and replace the fuel filter, fuel pump, or fuel pressure regulator as necessary.

4. Clean MAF Sensor

• Tools Required: MAF sensor cleaner
• Locate the MAF sensor and carefully remove it from the air intake path.
• Spray the cleaning solution onto the sensor components, avoiding direct contact with the wiring.
• Allow it to dry completely before reinstalling.

5. Inspect and Test Oxygen Sensors

• Tools Required: O2 sensor socket, multimeter
• Disconnect the electrical connector of the upstream oxygen sensor.
• Use a multimeter to check the sensor’s voltage output. It should fluctuate between 0.2V to 0.8V when the engine is running.
• If the sensor is faulty, replace it with a new unit.

6. Fuel Injector Inspection

• Tools Required: Multimeter, fuel injector cleaning kit (optional)
• Remove the fuel injectors from the fuel rail.
• Check the resistance of each injector using a multimeter and compare with specifications.
• If any injectors are defective, replace them. Optionally, clean the injectors using a cleaning kit.