what does P0171 code mean for my 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 necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Air Intake System

1. Check for Leaks

   • Visually inspect all vacuum hoses and the intake manifold for cracks or disconnections.
   • Use a smoke machine if available to detect hidden leaks.
   • Tighten or replace any loose or damaged hoses.

2. Clean MAF Sensor

   • Remove the MAF sensor using a Torx screwdriver.
   • Spray MAF cleaner on the sensor element and allow it to dry completely.
   • Reinstall the sensor securely.

3. Fuel System Check

1. Check Fuel Pressure
   • Connect a fuel pressure gauge to the fuel rail.
   • Turn the ignition to the "ON" position without starting the engine and check the pressure.
   • Compare the reading to manufacturer specifications (typically between 50-60 PSI).
   • If pressure is low, inspect and replace the fuel pump or fuel filter if necessary.

4. Address Oxygen Sensors

1. Inspect and Test Sensors
   • Locate the upstream oxygen sensor (pre-catalytic converter).
   • Use an OBD-II scanner to monitor the live data from the sensor.
   • Replace the sensor if readings are outside of specifications.

5. Reassemble and Test

• Reconnect all components and the negative battery terminal.
• Clear the error codes using the OBD-II scanner.