what does code P0171 indicate for my GMC Sierra T1XX (2019-Present)

Learn how to diagnose and fix P0171 lean fuel 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.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect Air Intake System

• Sub-steps:
  1. Visually inspect the air intake hoses for cracks or disconnections.
  2. Tighten any loose clamps or replace damaged hoses.
  3. Check the air filter and replace it if it is dirty or clogged.

3. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition on without starting the engine and check the pressure reading.
  3. Compare the reading to manufacturer specifications (usually between 55-62 psi).
  4. If the pressure is low, inspect the fuel pump and filter for issues.

4. Clean or Replace MAF Sensor

• Sub-steps:
  1. Disconnect the MAF sensor electrical connector.
  2. Remove the MAF sensor from the air intake duct.
  3. Clean the sensor using MAF sensor cleaner (do not use other cleaners).
  4. Reinstall the MAF sensor and reconnect the electrical connector.

5. Check Oxygen Sensors

• Sub-steps:
  1. Use a multimeter to check the voltage output of the upstream oxygen sensor.
  2. If the output is not within the normal range (typically 0.1-0.9 volts), consider replacing the sensor.
  3. Reinstall any components removed during inspection.