how to diagnose P0171 code on Ford F-150 13th Generation (2015-2020)

Ford F-150 13th Generation (2015-2020)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0171

3 min read

590 words

Problem Statement

Learn how to diagnose and fix P0171 lean fuel condition in Ford F-150 (2015-2020). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0171

Affected Component

Engine

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on electrical systems.
•Allow the engine to cool before opening any components to prevent burns.

Symptoms

•Check engine light illuminated
•Rough idle or stalling
•Decreased fuel efficiency
•Engine hesitation during acceleration
•Unusual engine noise (e.g., backfiring)
•Increased emissions

Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to confirm the P0171 code and check for any additional codes.
2
Inspect the air intake system for vacuum leaks, including hoses, gaskets, and the intake manifold.
3
Check the mass air flow (MAF) sensor for proper function by cleaning or replacing it if necessary.
4
Inspect fuel pressure using a fuel pressure gauge to ensure it meets manufacturer specifications.
5
Examine the fuel injectors for clogs or leaks and test their operation.
6
Check the oxygen sensor for proper operation and response to changes in fuel mixture.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Vacuum gauge
•Fuel pressure gauge
•Multimeter
•Torx or socket set
•Smoke machine (optional)

Parts Required

•MAF sensor (if replacement is needed)
•Fuel injectors (if replacement is needed)
•Oxygen sensor (if replacement is needed)

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Diagnostic Steps

1
Scan the vehicle's computer using an OBD-II scanner to confirm the P0171 code and check for any additional codes.
2
Inspect the air intake system for vacuum leaks, including hoses, gaskets, and the intake manifold.
3
Check the mass air flow (MAF) sensor for proper function by cleaning or replacing it if necessary.
4
Inspect fuel pressure using a fuel pressure gauge to ensure it meets manufacturer specifications.
5
Examine the fuel injectors for clogs or leaks and test their operation.
6
Check the oxygen sensor for proper operation and response to changes in fuel mixture.

Solution

1. Preparation

Gather necessary tools and parts.
Disconnect the vehicle battery.
Allow the engine to cool down.

2. Inspect Air Intake System

Visually inspect all vacuum hoses for cracks or disconnections.
Check the intake manifold gasket for leaks.
Use a smoke machine to help identify vacuum leaks.

3. Clean or Replace MAF Sensor

Remove the MAF sensor from the intake system using a Torx or socket wrench.
Clean the sensor with MAF cleaner and let it dry completely before reinstalling.
If cleaning does not resolve the issue, replace the MAF sensor with a new part.

4. Check and Test Fuel Pressure

Connect a fuel pressure gauge to the fuel rail Schrader valve.
Turn the ignition to the "ON" position (do not start the engine) and read the pressure.
Compare the reading to the manufacturer's specifications (typically around 50-60 psi for the F-150).
If pressure is low, inspect the fuel pump and filter for issues.

5. Inspect Fuel Injectors

Remove the fuel injectors from the fuel rail.
Visually inspect for any signs of clogging or leaking.
Use an injector cleaner or replace the injectors if they are faulty.

6. Check Oxygen Sensor

Use a multimeter to test the oxygen sensor's voltage output while the engine is running.
The voltage should fluctuate between 0.1 to 0.9 volts; if it remains steady, replace the sensor.