how to fix P0171 code in my Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  • Use a smoke machine or carb cleaner to detect leaks around hoses and the intake manifold.
  • If leaks are found, replace damaged hoses or reseal connections as necessary.

3. Check and Clean the MAF Sensor

• Sub-steps:
  • Locate the MAF sensor in the air intake duct.
  • Disconnect the electrical connector.
  • Remove the MAF sensor from the duct using a Torx or Phillips screwdriver.
  • Spray MAF sensor cleaner on the sensor elements and let it dry completely before reinstalling.
  • Reattach the MAF sensor and connector.

4. Test Fuel Pressure

• Sub-steps:
  • Locate the fuel rail and connect the fuel pressure gauge.
  • Turn the ignition to the "ON" position (do not start the engine) and observe the pressure reading.
  • Compare the reading to the specifications (usually around 50-60 psi for most Toyota engines).
  • If pressure is low, check the fuel pump and filter for issues.

5. Inspect and Test Fuel Injectors

• Sub-steps:
  • Remove the engine cover if necessary to access the fuel rail.
  • Inspect the injectors for signs of leakage or blockage.
  • Use an injector cleaner or ultrasonic cleaner if clogged.
  • Reinstall any removed components securely.

6. Check Engine Coolant Temperature Sensor

• Sub-steps:
  • Locate the coolant temperature sensor and disconnect the electrical connector.
  • Use a multimeter to measure resistance and compare it to the manufacturer’s specifications.
  • If the readings are out of spec, replace the sensor.