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Home/Cars/GMC/Sierra/T1XX (2019-Present)/what does P0171 code mean for my GMC Sierra T1XX (2019-Present)

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

GMC Sierra T1XX (2019-Present)

Error Codes
Severity: mediumDifficulty: mediumError Code: P01712-4 hours
3 min read
527 words

Problem Statement

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

Error Code
P0171
Affected Component
Engine
Estimated Time
2-4 hours

Safety Warnings

  • ⚠Disconnect battery before working on electrical systems.
  • ⚠Allow the engine to cool before inspecting components.

Symptoms

  • •Check engine light illuminated
  • •Rough idle or stalling
  • •Poor acceleration or loss of power
  • •Decreased fuel economy
  • •Unusual engine noise
  • •Increased emissions

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm P0171 and check for any additional codes.
  2. 2Inspect the air intake system for leaks, including hoses and intake manifold gaskets.
  3. 3Check the fuel pressure using a fuel pressure gauge to ensure it meets manufacturer specifications.
  4. 4Inspect the mass airflow (MAF) sensor for dirt or damage and perform a cleaning if required.
  5. 5Examine the oxygen sensors and ensure they are functioning properly.
  6. 6Check for vacuum leaks in the intake manifold and surrounding areas.

Solution

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.

Verification

After completing the repair, verify that the issue has been resolved:

  • ✓Test the affected component to ensure it functions correctly
  • ✓Check for any error codes or warning lights
  • ✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

  • •Follow the manufacturer's recommended maintenance schedule
  • •Address warning signs early before they develop into major issues
  • •Use quality parts and fluids recommended for your vehicle
  • •Keep detailed records of all repairs and maintenance

Tools & Equipment Required

  • •OBD-II scanner
  • •Fuel pressure gauge
  • •Torque wrench
  • •Screwdrivers (including Torx)
  • •MAF cleaner
  • •Smoke machine (optional)

Parts Required

  • •Mass airflow sensor (if defective)
  • •Oxygen sensor (if defective)
  • •Fuel pump (if defective)
  • •Fuel filter (if dirty)

Additional Information

Error Code
P0171
Affected Component
Engine
Estimated Time
2-4 hours
Difficulty
medium
Severity
medium
Tools Required
6 items
Parts Required
4 items

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