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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or damage.
  2. Replace any damaged hoses with OEM hoses.
  3. Use a smoke machine to detect any hidden leaks if necessary.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake between the air filter and throttle body.
  2. Disconnect the electrical connector.
  3. Remove the MAF sensor using a Torx or Phillips screwdriver.
  4. Clean the MAF sensor with MAF sensor cleaner. Allow it to dry completely.
  5. If cleaning doesn’t resolve the issue, replace the MAF sensor with a new one.

4. Check and Adjust Fuel Pressure

• Sub-steps:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Connect the fuel pressure gauge to the test port.
  3. Turn the ignition key to the "ON" position (do not start the engine) and check the pressure reading.
  4. If the pressure is below specifications (typically 40-50 psi for Honda Civic), check the fuel pump and fuel filter.
  5. Replace the fuel filter if clogged, or the fuel pump if it’s not providing adequate pressure.

5. Inspect and Replace ECT Sensor (if necessary)

• Sub-steps:
  1. Locate the ECT sensor, typically near the thermostat housing.
  2. Disconnect the electrical connector and remove the sensor using a socket.
  3. Install the new ECT sensor and reconnect the electrical connector.