how to diagnose P0171 lean code on Honda Pilot YF3 (2016-2022)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative terminal of the battery.
• Allow the engine to cool down before proceeding.

2. Inspect Air Intake System

• Tools Required: Socket set, flashlight, vacuum gauge
• Instructions:
  1. Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  2. Use a vacuum gauge to check for leaks in the intake system.
  3. Replace any damaged hoses and reattach any loose connections.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver
• Instructions:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and unscrew the sensor from the duct.
  3. Clean the sensor with a dedicated MAF cleaner and let it dry.
  4. Reinstall the sensor and reconnect the electrical connector.

4. Inspect Fuel System

• Tools Required: Fuel pressure gauge, socket set
• Instructions:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition on (do not start) and check the pressure reading; it should be within manufacturer specifications.
  3. If the pressure is low, check the fuel pump operation and replace the fuel filter if clogged.

5. Check Oxygen Sensor Operation

• Tools Required: Multimeter
• Instructions:
  1. Locate the upstream (pre-cat) oxygen sensor.
  2. Use a multimeter to measure the voltage output while the engine is running; it should oscillate between 0.1V and 0.9V.
  3. Replace the sensor if the readings are outside this range or if it is unresponsive.