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 required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Repair Air Intake System

• Sub-steps:
  1. Visually inspect all air intake hoses for cracks or loose fittings.
  2. Tighten or replace any damaged hoses.
  3. Check the throttle body for cleanliness; clean if necessary.
• Tools Required: Socket set, screwdrivers.

3. Test and Repair Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "On" position (do not start the engine) and check the fuel pressure.
  3. If pressure is below the manufacturer's specifications, check the fuel pump and fuel filter for issues and replace if needed.
• Tools Required: Fuel pressure gauge.

4. Clean or Replace Mass Air Flow Sensor

• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Remove the MAF sensor and inspect for dirt or damage.
  3. If dirty, clean the sensor with MAF cleaner. If damaged, replace the sensor.
• Tools Required: Torx or socket set, MAF cleaner.

5. Inspect and Test Oxygen Sensors

• Sub-steps:
  1. Locate the upstream oxygen sensor (usually before the catalytic converter).
  2. Use a multimeter to check the voltage output of the sensor.
  3. If the sensor is not functioning correctly, replace it.
• Tools Required: Multimeter, O2 sensor socket.