how to fix the P0171 lean code on my GMC Sierra T1XX (2019-Present)

Learn how to diagnose and fix P0171 lean code in GMC Sierra T1XX. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal for safety.
• Allow the engine to cool down before beginning work.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps, replacement vacuum hoses (if needed)
• Inspect all vacuum lines for cracks or loose connections.
• Use a vacuum gauge to check the intake manifold for leaks.
• Replace any damaged hoses or tighten loose connections.

3. Check and Clean the MAF Sensor

• Tools Required: MAF sensor cleaner, clean cloth
• Locate the MAF sensor in the air intake path.
• Disconnect the electrical connector and remove the MAF sensor carefully.
• Spray the MAF sensor with MAF cleaner and let it dry completely before reinstalling.

4. Test and Replace Fuel Pressure Regulator

• Tools Required: Fuel pressure gauge, socket set
• Connect a fuel pressure gauge to the fuel rail service port.
• Turn the ignition to the "ON" position without starting the engine and check the pressure reading.
• If the pressure is below manufacturer specifications, replace the fuel pressure regulator.

5. Inspect Fuel Injectors

• Tools Required: Fuel injector cleaner, multimeter (for electrical testing)
• Check each fuel injector for clogs using a fuel injector cleaner.
• Perform a resistance test with a multimeter to ensure proper electrical function.
• Replace any faulty injectors as necessary.

6. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear any stored error codes.
• Restart the engine and monitor for any reoccurring issues.