what does it mean when my Toyota Corolla E170 (2013-2019) has a P0171 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down completely before starting repairs.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect all air intake hoses and connections for visible cracks or disconnections.
  2. Replace any damaged hoses.
  3. Check the air filter and replace if clogged or dirty.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Carefully disconnect the electrical connector.
  3. Remove the MAF sensor using a socket set.
  4. Clean the sensor with MAF sensor cleaner; do not touch the sensing elements.
  5. Reinstall the sensor and reconnect the electrical connector. If cleaning does not resolve the issue, replace the MAF sensor.

4. Inspect Fuel System

• Sub-steps:
  1. Check the fuel pressure using a fuel pressure gauge.
  2. If pressure is low, inspect the fuel pump and filter. Replace if necessary.
  3. Verify that the fuel injectors are functioning correctly and are not clogged.

5. Check Oxygen Sensors

• Sub-steps:
  1. Use a multimeter to test the voltage output of the upstream oxygen sensor.
  2. If readings are below specifications, consider replacing the sensor.
  3. Reconnect everything after inspections and repairs.