how to fix P0171 lean condition code on my Toyota Highlander

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery negative terminal to prevent electrical shorts.

2. Inspect and Replace Vacuum Hoses

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold.
  2. Replace any cracked or damaged hoses with new ones.
  3. Ensure all connections are secure.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Remove the MAF sensor carefully using a screwdriver.
  3. Clean the sensor with MAF cleaner and allow it to dry, or replace if damaged.
  4. Reinstall the MAF sensor and secure it properly.

4. Check Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition to the "ON" position without starting the engine to check the fuel pressure.
  3. Compare the reading to the manufacturer specifications; if low, replace the fuel pump or filter as necessary.

5. Inspect and Clean Throttle Body

• Sub-steps:
  1. Remove the air intake duct connected to the throttle body.
  2. Use throttle body cleaner to clean the inside of the throttle body.
  3. Ensure the throttle plate moves freely and is not obstructed.
  4. Reinstall the air intake duct.

6. Reconnect Battery

• Reconnect the battery negative terminal once all repairs are completed.