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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the engine is cool before starting work.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a smoke machine to detect vacuum leaks if necessary.
  3. Replace any damaged hoses or gaskets identified during inspection.

3. Clean Mass Air Flow (MAF) Sensor

• Tools Required: MAF cleaner spray, Torx screwdriver
• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the screws holding the sensor in place.
  3. Spray the MAF sensor with a specialized MAF cleaner and let it dry completely.
  4. Reinstall the sensor and reconnect the electrical connector.

4. Check Fuel Delivery System

• Tools Required: Fuel pressure gauge
• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition key to the "ON" position without starting the engine to check the pressure.
  3. Compare the reading with manufacturer specifications (should typically be around 50-60 psi).
  4. If pressure is low, inspect the fuel pump and filter for issues and replace if necessary.

5. Replace Oxygen Sensor (if necessary)

• Tools Required: Oxygen sensor socket, wrench
• Sub-steps:
  1. Locate the upstream oxygen sensor on the exhaust manifold.
  2. Disconnect the electrical connector and use the oxygen sensor socket to remove it.
  3. Install the new oxygen sensor and reconnect the wiring.
  4. Torque the sensor according to manufacturer specifications (usually around 30-40 ft-lbs).