how to diagnose P0171 code on Honda Accord 9th Generation (2013-2017)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Inspect and Repair Air Intake System

1. Visual Inspection

   • Check all vacuum hoses for cracks or disconnections.
   • Inspect the intake manifold gasket for leaks.
   • Ensure the air filter is clean and correctly installed.

2. Repair or Replace

   • Replace any damaged vacuum hoses or gaskets.
   • Clean or replace the air filter if necessary.

3. Clean or Replace the MAF Sensor

1. Remove MAF Sensor

   • Disconnect the MAF sensor wiring harness.
   • Unscrew the MAF sensor from the air intake duct.

2. Cleaning

   • Use MAF sensor cleaner to clean the sensor element.
   • Allow the sensor to dry completely before reinstallation.

3. Reinstall MAF Sensor

   • Secure the MAF sensor back in place and reconnect the wiring harness.

4. Check Fuel System

1. Test Fuel Pressure

   • Connect a fuel pressure gauge to the fuel rail.
   • Turn the ignition on (do not start the engine) and check if the pressure meets specifications (usually around 40-50 psi for Honda Accord).

2. Replace Fuel Filter or Pump

   • If pressure is low, replace the fuel filter or consider replacing the fuel pump if it is faulty.

5. Inspect Oxygen Sensors

1. Remove Oxygen Sensor

   • Use an oxygen sensor socket to remove the upstream (pre-catalytic converter) sensor.

2. Test Sensor

   • Use a multimeter to check sensor voltage output. It should fluctuate between 0.1V and 0.9V when the engine is running.

3. Replace if Faulty

   • If the readings are out of range, replace the oxygen sensor.