why is my Ford F-150 running lean and what does P0171 mean

Learn how to diagnose and fix P0171 engine running lean issue in Ford F-150. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before working on components.

2. Inspect Air Intake System

• Remove the air intake duct to access the MAF sensor.
• Carefully inspect and replace any damaged vacuum hoses.
• Tighten any loose clamps or connections in the air intake path.

3. Clean or Replace MAF Sensor

• Remove the MAF sensor from the air intake system.
• Use MAF sensor cleaner to clean the sensor. Avoid touching the sensing elements.
• Reinstall the sensor and ensure it is securely connected.

4. Check and Adjust Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Start the engine and observe the fuel pressure reading; it should meet the manufacturer's specifications (typically around 30-60 psi).
• If the pressure is low, check the fuel pump operation and replace the fuel filter if necessary.

5. Inspect Throttle Body

• Remove the throttle body from the intake manifold.
• Clean the throttle body using throttle body cleaner to remove any carbon buildup.
• Reinstall the throttle body and ensure the gasket is intact.

6. Test Oxygen Sensors

• Use a multimeter to test the voltage output of the upstream oxygen sensor.
• If the readings are out of the manufacturer's specified range, consider replacing the oxygen sensor.