how to fix P0171 code on my Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before starting work.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum lines for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect leaks around the intake manifold and vacuum hoses.
  3. Replace any damaged hoses or gaskets found during inspection.
• Tools Required: Smoke machine or carburetor cleaner, basic hand tools.

3. Test and Replace Fuel Components

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail; turn the ignition to the ON position (do not start) and check the pressure.
  2. If pressure is below specifications, check the fuel pump, filter, and relay.
  3. If necessary, replace the fuel filter or fuel pump.
• Tools Required: Fuel pressure gauge, socket set.

4. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the MAF sensor electrical connector.
  2. Remove the MAF sensor from the intake duct.
  3. Clean the sensor using MAF cleaner spray; allow it to dry completely.
  4. If cleaning does not help, replace the MAF sensor with a new one.
• Tools Required: MAF cleaner, screwdriver.

5. Inspect and Clean Fuel Injectors

• Sub-steps:
  1. Disconnect the fuel injector connectors.
  2. Remove the fuel rail and injectors from the engine.
  3. Clean fuel injectors using an ultrasonic cleaner or a fuel injector cleaning kit.
  4. Reinstall the injectors and fuel rail.
• Tools Required: Ultrasonic cleaner (if needed), socket set.

6. Recheck Oxygen Sensors

• Sub-steps:
  1. Inspect the wiring and connectors of the upstream and downstream oxygen sensors for damage.
  2. Use a multimeter to test the sensors’ voltage output while the engine is running.
  3. Replace any faulty oxygen sensors.
• Tools Required: Multimeter, basic hand tools.