my Toyota Corolla E210 (2019-2024) has a check engine light and code P0171, what does it mean?

Solution

1. Preparation

• Gather necessary tools and equipment.
• Disconnect the battery to ensure safety.
• Allow the engine to cool before working on components.

2. Inspect and Repair the Air Intake System

• Sub-steps:
  1. Visually inspect all air intake hoses and connections for cracks or disconnections.
  2. Replace any damaged hoses or seals.
  3. Ensure the air filter is clean; replace if dirty.

3. Check and Clean the MAF Sensor

• Sub-steps:
  1. Disconnect the electrical connector from the MAF sensor.
  2. Remove the MAF sensor from the intake duct.
  3. Use MAF sensor cleaner to carefully clean the sensor element.
  4. Reinstall the MAF sensor and reconnect the electrical connector.

4. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition key to the "ON" position without starting the engine and check the pressure reading.
  3. Compare the pressure reading to manufacturer specifications (typically 40-50 psi).
  4. If pressure is low, check the fuel pump and filter for issues.

5. Inspect and Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Use a multimeter to test the voltage output of the upstream sensor while the engine is running.
  3. Replace the oxygen sensor if the voltage readings are outside the normal range (0.1 to 0.9 volts).