how to diagnose P0171 code in Honda Civic 9th Generation (2012-2015)

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to avoid any electrical shorts.
• Allow the engine and components to cool if previously running.

2. Inspect and Repair Air Intake System

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

3. Fuel System Check

• 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 pressure against the manufacturer's specifications (typically around 45-50 psi).
  • If the pressure is low, check the fuel pump, fuel filter, and relay. Replace as necessary.

4. MAF Sensor Maintenance

• Sub-steps:
  • Disconnect the MAF sensor connector.
  • Remove the sensor from the air intake duct.
  • Clean the MAF sensor using MAF cleaner spray (do not touch the sensor element).
  • Reinstall the MAF sensor and reconnect the connector securely.

5. Oxygen Sensor Inspection

• Sub-steps:
  • Locate the upstream oxygen sensor (before the catalytic converter).
  • Check the wiring and connector for damage.
  • If necessary, use a multimeter to test the sensor's voltage output while the engine is running (should fluctuate between 0.1 to 0.9 volts).
  • Replace the sensor if it is not functioning properly.