how to fix P0171 code on Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum lines and connections from the air intake to the engine for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to identify leaks by applying it around suspected areas and observing for changes in engine RPM.
  3. Replace any damaged vacuum hoses or gaskets identified during inspection.

3. Clean or Replace the MAF Sensor

• Sub-steps:
  1. Disconnect the electrical connector from the MAF sensor.
  2. Remove the MAF sensor using a Torx screwdriver, taking care not to damage it.
  3. Clean the MAF sensor with MAF sensor cleaner, ensuring no residue remains.
  4. If damaged, replace the MAF sensor with a new one.
  5. Reinstall the MAF sensor, reconnect the electrical connector, and ensure it is secure.

4. Fuel System Inspection

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "On" position without starting to check the initial fuel pressure.
  3. Start the engine and monitor the fuel pressure; it should be within the manufacturer’s specifications (typically around 43-50 psi).
  4. If pressure is low, inspect the fuel pump and filter for issues and replace as necessary.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail assembly from the engine.
  2. Inspect each injector for clogs by checking for proper spray patterns using a fuel injector tester or by manually inspecting for obstructions.
  3. Clean or replace any faulty fuel injectors.
  4. Reinstall the fuel rail ensuring all connections are tight.