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 tools and parts needed for the repair.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps, and rubber grommets.
• Inspect all vacuum lines and gaskets for cracks or disconnections.
• Replace any damaged hoses or gaskets, ensuring secure connections.
• Check the throttle body gasket and replace if necessary.

3. Clean or Replace MAF Sensor

• Tools Required: MAF sensor cleaner, screwdriver.
• Disconnect the MAF sensor connector.
• Remove the MAF sensor from the air intake tube.
• Clean the sensor using MAF cleaner, avoiding contact with the sensor element.
• Reinstall the MAF sensor and reconnect the connector.

4. Check Fuel System

• Tools Required: Fuel pressure gauge, wrenches.
• Connect the fuel pressure gauge to the fuel rail test port.
• Turn the ignition key to the "On" position (do not start) to check fuel pressure.
• Compare the pressure reading to manufacturer specifications. Replace the fuel filter if needed and ensure the fuel pump is functioning correctly.

5. Inspect and Test Fuel Injectors

• Tools Required: Noid light, multimeter.
• Connect a noid light to each fuel injector connector to ensure they are receiving power.
• If the injectors are not firing, test the wiring for continuity.
• If injectors are clogged, clean them using an injector cleaning kit or replace them if necessary.

6. Test and Replace Oxygen Sensors (if needed)

• Tools Required: O2 sensor socket, multimeter.
• If the oxygen sensors are suspected to be faulty, test their output voltage with a multimeter.
• Replace the sensor if readings are outside the normal range.