how to fix the P0171 code on my Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before starting any 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.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Remove the MAF sensor from the air intake duct using a socket set.
  2. Clean the MAF sensor with MAF cleaner spray; allow it to dry completely.
  3. If cleaning does not resolve issues, replace the MAF sensor with a new one.

4. Check and Adjust Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition on (do not start the engine) and check the pressure reading.
  3. If the pressure is below specifications, inspect the fuel pump and filter; replace if necessary.
  4. If the fuel filter is clogged, replace it and check for any kinks in the fuel line.

5. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail assembly to access the injectors.
  2. Inspect each injector for clogs and electrical connection issues.
  3. Clean injectors using an ultrasonic cleaner or replace them if necessary.

6. Reassemble and Final Checks

• Sub-steps:
  1. Reinstall the fuel rail and MAF sensor.
  2. Reconnect any vacuum lines removed during repair.
  3. Reconnect the battery and start the engine; check for leaks and ensure smooth operation.