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

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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety during repair.
• Allow the engine to cool down before starting work.

2. Inspect and Repair Air Intake System

• Tools Required: Socket set, screwdrivers, vacuum gauge, air intake cleaner
• Check all air intake hoses and connections for visible cracks or damage. Replace any damaged components.
• Ensure that the air filter is clean and free of debris. Replace if necessary.
• Reassemble the air intake system securely.

3. Test and Clean the MAF Sensor

• Tools Required: MAF cleaner, torx screwdriver
• Locate the MAF sensor in the air intake duct.
• Disconnect the electrical connector and remove the sensor.
• Clean the MAF sensor with MAF cleaner according to the manufacturer’s instructions.
• Reinstall the sensor and reconnect the electrical connector.

4. Fuel System Inspection

• Tools Required: Fuel pressure gauge, socket set
• Attach the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "On" position (do not start the engine) and record the fuel pressure. It should be within the manufacturer's specified range.
• If the pressure is low, inspect the fuel pump and fuel filter for blockages or failures.

5. Vacuum Leak Repair

• Tools Required: Smoke machine or carburetor cleaner
• Use a smoke machine to detect vacuum leaks or spray carburetor cleaner around potential leak points while the engine is running.
• If the engine RPM changes, a vacuum leak is present, and the leaking component should be replaced or repaired.

6. Final Checks

• Reconnect the battery.
• Clear the P0171 code using the OBD-II scanner.
• Start the engine and allow it to reach operating temperature while monitoring for any new codes.