how to fix a P0171 code on my Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

• Gather all tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down before working on it.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum lines connected to the intake manifold for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to identify any leaks around the intake manifold gasket.
  3. Replace any damaged hoses and reseal the intake manifold gasket if necessary.

3. Clean or Replace the MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the sensor from the duct.
  3. Clean the MAF sensor using MAF cleaner spray (do not use other cleaners).
  4. If cleaning does not resolve the issue, replace the MAF sensor with a new unit.

4. Check and Adjust Fuel Pressure

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail service port.
  2. Turn the ignition to the "ON" position (do not start the engine) and check the pressure reading.
  3. If the pressure is below specifications, check the fuel pump and filter for clogs or failures, and replace if necessary.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail with the injectors attached.
  2. Inspect the injectors for any signs of clogging or leaks.
  3. Clean the injectors using an injector cleaning kit or replace them if they are faulty.