what does it mean when my Toyota RAV4 XA50 (2019-2024) has a P0171 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the vehicle is on a level surface and securely raised if needed.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses for cracks or disconnections.
  • Use a smoke machine or carburetor cleaner to identify leaks.
  • Replace any damaged hoses or gaskets as needed.

3. Clean or Replace MAF Sensor

• Sub-steps:
  • Remove the MAF sensor from the air intake duct.
  • Spray MAF cleaner onto the sensor elements; do not touch them directly.
  • Allow the sensor to dry completely before reinstalling.
  • If the sensor is damaged, replace it with a new one.

4. Check Fuel System

• Sub-steps:
  • Connect a fuel pressure gauge to the fuel rail.
  • Turn the ignition to the "ON" position without starting the engine and check the fuel pressure.
  • If pressure is low, inspect the fuel pump and filter; replace them if necessary.

5. Inspect Oxygen Sensors

• Sub-steps:
  • Locate the upstream oxygen sensor (pre-catalytic converter).
  • Disconnect the sensor and use a multimeter to check the voltage output; it should oscillate between 0.1V and 0.9V when the engine is running.
  • Replace the sensor if it does not meet specifications.

6. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0171 code from the ECM.
• Start the engine and observe for any reoccurrence of the code.