how to diagnose P0171 code in Ford F-150 Fourteenth Generation (2021-present)

Learn how to diagnose and fix P0171 lean air-fuel mixture in Ford F-150. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and necessary parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the battery to ensure safety while working on the vehicle.

2. Inspect Air Intake System

• Tools Required: Screwdriver set, flashlight
• Inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
• Check the intake manifold gaskets for leaks by visually inspecting and, if necessary, using a smoke test to identify leaks.
• Tighten any loose clamps on the air intake system.

3. Clean the MAF Sensor

• Tools Required: MAF sensor cleaner, soft cloth
• Remove the MAF sensor from the air intake tube.
• Spray MAF sensor cleaner onto the sensor elements and allow them to dry completely.
• Reinstall the MAF sensor ensuring a secure connection.

4. Test Fuel Pressure

• Tools Required: Fuel pressure gauge
• Locate the fuel rail and connect the fuel pressure gauge to the Schrader valve.
• Turn the ignition to the "ON" position (do not start) and check the fuel pressure reading. It should be within the manufacturer's specified range.
• If pressure is low, inspect the fuel pump and fuel filter for issues.

5. Inspect Fuel Injectors

• Tools Required: Fuel injector cleaning kit (if needed), multimeter
• Visually inspect fuel injectors for leaks or carbon buildup.
• Use a multimeter to check the resistance of the injectors; compare readings with specifications.
• If injectors are clogged, consider cleaning them with a fuel injector cleaning kit.

6. Check Oxygen Sensors

• Tools Required: O2 sensor socket
• Using the O2 sensor socket, remove the upstream oxygen sensor.
• Inspect the sensor for contamination or damage and replace if necessary.
• Reinstall the sensor and clear any codes from the ECM.