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Home/Cars/GMC/Sierra/T1XX (2019-Present)/how to diagnose a check engine light on GMC Sierra T1XX (2019-Present)

how to diagnose a check engine light on GMC Sierra T1XX (2019-Present)

GMC Sierra T1XX (2019-Present)

Error Codes
Severity: mediumDifficulty: mediumError Code: P01711-3 hours
3 min read
519 words

Problem Statement

Learn how to diagnose and fix the check engine light issue on GMC Sierra T1XX (2019-Present). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code
P0171
Affected Component
Engine
Estimated Time
1-3 hours

Safety Warnings

  • ⚠Disconnect the battery before working on electrical systems to prevent shocks or short circuits
  • ⚠Ensure the engine is cool before performing any inspection or repairs to avoid burns

Symptoms

  • •Check engine light illuminated on the dashboard
  • •Possible rough idle or engine stalling
  • •Loss of power during acceleration
  • •Decreased fuel economy
  • •Increased emissions or unusual exhaust smells

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to retrieve diagnostic trouble codes (DTCs)
  2. 2Interpret the error codes and note their specific descriptions
  3. 3Check for any technical service bulletins (TSBs) related to the retrieved codes
  4. 4Inspect the vehicle's fuel, air intake, and exhaust systems for visible issues
  5. 5Verify the condition of spark plugs and ignition coils if misfire codes are present
  6. 6Inspect vacuum hoses and seals for leaks, particularly in the intake manifold area

Solution

Solution

1. Preparation

  • Tools Required: OBD-II scanner, socket set, multimeter, torque wrench, vacuum gauge.
  • Disconnect the vehicle's battery to prevent electrical shorts.
  • Allow the engine to cool if it has been running to avoid burns.

2. Code Clearing and Component Inspection

  1. Connect the OBD-II scanner to the vehicle's diagnostic port.
  2. Retrieve and document any stored error codes.
  3. Clear the codes and observe if they return after a short test drive.
  4. Visually inspect engine components such as the air filter, fuel lines, and exhaust for any signs of damage or wear.

3. Addressing Specific Codes

  1. Based on the retrieved DTCs, address each issue:
    • For P0171/P0174 (lean condition), check fuel injectors and fuel pressure.
    • For P0300 (random misfire), inspect ignition components and fuel quality.
    • For P0420 (catalytic converter efficiency), check for exhaust leaks and test the O2 sensors.
  2. Replace any faulty components identified during inspections (e.g., spark plugs, fuel injectors).

4. Reassembly and Testing

  1. Reassemble any components removed during the inspection.
  2. Reconnect the battery and ensure all connections are secure.
  3. Start the engine and let it idle to ensure no CEL is illuminated.

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
  • •Socket set
  • •Multimeter
  • •Torque wrench
  • •Vacuum gauge

Parts Required

  • •Spark plugs (if worn)
  • •Fuel injectors (if faulty)
  • •O2 sensors (if malfunctioning)

Additional Information

Error Code
P0171
Affected Component
Engine
Estimated Time
1-3 hours
Difficulty
medium
Severity
medium
Tools Required
5 items
Parts Required
3 items

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