how to diagnose a P0171 code on Honda Accord Eleventh Generation (2023-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting repairs.

2. Inspect and Repair Air Intake System

• Sub-steps:
  • Visually inspect the air intake duct, intake manifold, and all associated vacuum hoses for damage or disconnections.
  • Use a smoke machine or aerosol can of carburetor cleaner to check for vacuum leaks; listen for hissing sounds or observe any increase in RPMs as you apply the cleaner.
  • Replace any damaged hoses or components as necessary.

3. Check and Clean MAF Sensor

• Sub-steps:
  • Locate the MAF sensor, typically found between the air filter and throttle body.
  • Disconnect the electrical connector and remove the sensor using a Torx or socket wrench.
  • Clean the MAF sensor with MAF sensor cleaner (do not use other cleaning agents).
  • Reinstall the sensor and reconnect the electrical connector.

4. Test Fuel Pressure

• Sub-steps:
  • Connect a fuel pressure gauge to the fuel rail's test port.
  • Turn the ignition on (do not start the engine) and read the pressure; it should match the specifications found in the service manual.
  • If the pressure is low, check the fuel pump, fuel filter, and fuel injectors for any issues.

5. Inspect and Replace Oxygen Sensors (if necessary)

• Sub-steps:
  • Locate the upstream (pre-catalytic) oxygen sensor; this is usually before the catalytic converter.
  • Disconnect the electrical connector and remove the sensor using an oxygen sensor socket.
  • Install the new sensor and reconnect the electrical connector.