how to fix P0171 code in Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, fuel pressure gauge, vacuum gauge, basic hand tools (sockets, wrenches).
• Ensure the vehicle is parked on a level surface and the engine is off.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a vacuum gauge to check for leaks; if necessary, apply a smoke test to identify hard-to-find leaks.
  3. Replace any damaged hoses or gaskets.
  4. Reconnect the negative battery terminal.

3. Clean or Replace MAF Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the sensor.
  3. Clean the MAF sensor using MAF cleaner spray; do not touch the sensing elements.
  4. If damaged, replace the MAF sensor with a new one.
  5. Reinstall the sensor and reconnect the electrical connector.

4. Test Fuel Pressure

• Sub-steps:
  1. Locate the fuel rail and connect the fuel pressure gauge.
  2. Turn the ignition to the "ON" position without starting the engine and check the fuel pressure.
  3. Compare the reading with the manufacturer’s specifications (typically around 30-50 PSI for Honda).
  4. If pressure is low, check the fuel pump and filter; replace them if necessary.

5. Inspect and Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-cat) oxygen sensor.
  2. Disconnect the electrical connector and use a multimeter to test voltage output while the engine is running.
  3. Replace the oxygen sensor if it does not produce a voltage signal between 0.1V and 0.9V while the engine operates.
  4. Reconnect the sensor and clear the code with an OBD-II scanner.