how to diagnose the P0174 code on my Ford F-150 Fourteenth Generation (2021-present)

Solution

1. Preparation

• Gather tools needed: OBD-II scanner, fuel pressure gauge, multimeter, basic hand tools (sockets, wrenches).
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect Air Intake System

• Remove the air intake duct and inspect for cracks or loose connections.
• Check the throttle body for carbon buildup and clean it if necessary.
• Reconnect all components securely after inspection.

3. Check Fuel Pressure

• Connect the fuel pressure gauge to the fuel rail's test port.
• Turn the ignition to the "on" position (do not start) to check the pressure reading.
• The pressure should match the specifications in the service manual (typically around 50-60 psi). If low, check the fuel pump and filter.

4. Inspect MAF Sensor

• Locate the MAF sensor in the air intake path.
• Disconnect the electrical connector and remove the sensor.
• Clean the MAF sensor with MAF cleaner spray and allow it to dry before reinstalling.
• Reconnect the sensor and electrical connector.

5. Examine Oxygen Sensors

• Use a multimeter to test the oxygen sensors for voltage output.
• If the readings are outside the expected range (0.1V to 0.9V for switching sensors), consider replacing the faulty sensor.
• Reinstall the sensors after inspection.

6. Inspect Vacuum Lines

• Visually check all vacuum hoses connected to the intake manifold for damage or disconnections.
• Replace any damaged hoses and ensure all connections are tight.

7. Test Engine Coolant Temperature Sensor

• Use a multimeter to check the resistance of the ECT sensor at various temperatures.
• If the readings are out of spec, replace the ECT sensor.