what does a P0171 code indicate for my Toyota RAV4 Fourth Generation (2013-2018)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shock.
• Ensure the engine is cool before starting work.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses and connections for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to detect leaks.
  • Replace any damaged hoses or gaskets found during inspection.

3. Clean or Replace the MAF Sensor

• Sub-steps:
  • Disconnect the electrical connector and remove the MAF sensor from the intake.
  • Clean the MAF sensor with MAF cleaner spray, avoiding the use of any other cleaners.
  • If cleaning does not resolve issues, replace the MAF sensor with a new one.

4. Check and Adjust Fuel Pressure

• Sub-steps:
  • Connect a fuel pressure gauge to the fuel rail service port.
  • Turn the ignition to the "on" position (without starting) and check the fuel pressure.
  • If pressure is below specifications (typically 30-50 psi), inspect the fuel pump and filter for issues and replace as necessary.

5. Inspect and Clean Fuel Injectors

• Sub-steps:
  • Remove the fuel rail and inspect injectors for dirt and clogs.
  • Use a fuel injector cleaner to clean the injectors or replace them if malfunctioning.
  • Reinstall the fuel rail and ensure all connections are secure.

6. Check Oxygen Sensors

• Sub-steps:
  • Use a multimeter to test the upstream oxygen sensor's voltage output.
  • Replace the upstream oxygen sensor if readings are out of the specified range.