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

Solution

1. Preparation

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

2. Inspect and Repair Air Intake System

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

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the sensor wiring harness.
  3. Remove the MAF sensor using the appropriate socket.
  4. Clean the MAF sensor with MAF cleaner or replace it if damaged.

4. Check and Repair Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the ON position (do not start) to check fuel pressure.
  3. If pressure is below the manufacturer specification, inspect the fuel pump and fuel filter for replacement.

5. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream oxygen sensor (before the catalytic converter).
  2. Disconnect the sensor wiring harness.
  3. Remove the sensor using an oxygen sensor socket.
  4. Install a new sensor, ensuring to apply anti-seize compound on the threads before installation.

6. Reassemble and Reset Codes

• Sub-steps:
  1. Reconnect all components and ensure all connections are secure.
  2. Reconnect the negative battery terminal.
  3. Use the OBD-II scanner to clear the P0171 code.