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

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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Inspect and Repair Air Intake System

• Inspect the Air Filter: Remove the air filter and check for dirt or blockages. Replace if necessary.
• Check Air Ducts: Visually inspect all air ducts leading to the throttle body for cracks or loose connections. Replace damaged ducts.
• Tighten Clamps: Ensure all clamps are secure to prevent air leaks.

3. Clean or Replace MAF Sensor

• Remove MAF Sensor: Disconnect the wiring harness and unscrew the MAF sensor from the air intake.
• Clean the MAF Sensor: Use MAF sensor cleaner to spray the sensor elements carefully; let it dry completely before reinstalling.
• Reinstall the Sensor: Attach it back securely and reconnect the wiring harness.

4. Check Fuel Pressure

• Connect Fuel Pressure Gauge: Locate the fuel rail and connect the gauge according to the manufacturer's instructions.
• Test Fuel Pressure: Turn the ignition to the "ON" position (without starting) and check if the pressure matches manufacturer specifications. If pressure is low, proceed to check the fuel pump and filter.

5. Inspect Fuel Injectors

• Remove Fuel Injectors: Carefully disconnect the fuel rail and remove the injectors.
• Clean or Replace Injectors: Use a fuel injector cleaning kit or replace faulty injectors as necessary.
• Reinstall Fuel Injectors: Ensure proper seating and reconnect the fuel rail.

6. Inspect Vacuum Lines

• Visual Check: Inspect all vacuum lines for cracks or disconnections.
• Replace Damaged Lines: If any lines are worn or cracked, replace them with new vacuum lines.