how to fix P0171 code on my Honda Civic 9th Generation (2012-2015)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  • Visually inspect all vacuum hoses for cracks, splits, or disconnections.
  • Use a smoke machine or propane torch (without igniting) to detect leaks.
  • Replace any damaged hoses with new ones.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner
• Sub-steps:
  • Disconnect the MAF sensor connector.
  • Remove the MAF sensor using a Torx or socket wrench.
  • Clean the sensor with MAF cleaner; do not touch the sensor element.
  • If cleaning does not resolve the issue, replace the MAF sensor with a new one.

4. Fuel System Inspection

• Sub-steps:
  • Connect a fuel pressure gauge to the fuel rail.
  • Turn the ignition to the ON position (do not start) and check fuel pressure.
  • If pressure is below specifications, inspect and replace the fuel filter and check the fuel pump operation.
  • Test the fuel injectors using a multimeter for resistance and functionality, replacing any faulty injectors.

5. Oxygen Sensor Inspection

• Sub-steps:
  • Inspect the upstream oxygen sensor wiring and connector for damage.
  • Use a multimeter to check the sensor's voltage output while the engine is running.
  • If the sensor is faulty, replace it with a new one.