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What are the symptoms of a failing thermostat in a 2019 Chevrolet Silverado 1500? - Chevrolet Silverado 1500
Home/Cars/Chevrolet/Silverado 1500/T1XX (2019-2023)/What are the symptoms of a failing thermostat in a 2019 Chevrolet Silverado 1500?

What are the symptoms of a failing thermostat in a 2019 Chevrolet Silverado 1500?

Chevrolet Silverado 1500 T1XX (2019-2023)

Error Codes
2 hours
Time
medium
Difficulty
medium
Severity
Error Code: P0128
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ProblemSymptomsDiagnosisSolution
ProblemSymptomsDiagnosisSolution
4 min read
778 words

Problem Statement

Learn about the symptoms of a failing thermostat in a 2019 Chevrolet Silverado 1500, diagnostic steps, and repair instructions.

Error Code
P0128
Affected Component
thermostat
Estimated Time
2 hours

Symptoms

  • •Overheating Engine
  • •Engine Running Cold
  • •Coolant Leaks
  • •Poor Fuel Efficiency
  • •Check Engine Light

Diagnostic Steps

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

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
  • •Infrared thermometer
  • •Basic hand tools (screwdrivers, socket set)
  • •Coolant catch pan
  • •Safety gloves and goggles

Additional Information

Error Code
P0128
Affected Component
thermostat
Estimated Time
2 hours
Difficulty
medium
Severity
medium
Tools Required
5 items

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Back to Generation
1. Overheating Engine
  • Symptoms: The engine temperature gauge may rise above the normal range, often to the red zone.
  • Cause: A stuck closed thermostat prevents coolant from flowing to the radiator, causing the engine to overheat.
2. Engine Running Cold
  • Symptoms: The temperature gauge may remain lower than normal, and the heater may not produce warm air.
  • Cause: A stuck open thermostat allows coolant to flow continuously, preventing the engine from reaching its optimal operating temperature.
3. Coolant Leaks
  • Symptoms: Puddles of coolant under the vehicle or visible coolant on engine components.
  • Cause: A failed thermostat may cause excessive pressure or overheating, leading to leaks in the cooling system.
4. Poor Fuel Efficiency
  • Symptoms: Noticeable decrease in miles per gallon (MPG).
  • Cause: An engine that runs too cold (due to a stuck open thermostat) can lead to incomplete combustion and inefficient fuel usage.
5. Check Engine Light
  • Symptoms: The check engine light may illuminate on the dashboard.
  • Cause: This can be triggered by the engine control module (ECM) detecting irregular temperature readings.
Tools Required
  • OBD-II scanner
  • Infrared thermometer
  • Basic hand tools (screwdrivers, socket set)
  • Coolant catch pan
  • Safety gloves and goggles
Step 1: Scan for Codes
  • Action: Use an OBD-II scanner to check for any diagnostic trouble codes (DTCs) related to the cooling system.
  • Expected Outcome: Look for codes such as P0128 (coolant temperature below thermostat regulating temperature).
Step 2: Check Engine Temperature
  • Action: Start the engine and let it idle. Monitor the temperature gauge on the dashboard.
  • Expected Outcome: The gauge should rise steadily to the middle of the range. If it doesn’t reach normal operating temperature, the thermostat may be stuck open.
Step 3: Infrared Thermometer Test
  • Action: After the engine has been running for about 10 minutes, use an infrared thermometer to check the temperature of the upper radiator hose.
  • Expected Outcome: If the hose is cold or only slightly warm while the engine is hot, the thermostat is likely stuck closed.
Step 4: Visual Inspection
  • Action: Inspect for any coolant leaks around the thermostat housing.
  • Expected Outcome: Look for signs of coolant seeping or dripping.
Step 5: Test Driving
  • Action: Take the vehicle for a short drive. Note any temperature fluctuations or changes in engine performance.
  • Expected Outcome: Overheating or lack of heat from the heater could indicate thermostat issues.
Repair Instructions

If the thermostat is diagnosed as faulty, follow these steps to replace it:

Tools Required
  • Socket set
  • Wrench set
  • Torque wrench
  • Coolant catch pan
  • New thermostat
  • New gasket (if applicable)
  • Coolant (if needed)
  • RTV silicone (if applicable)
Step 1: Prepare the Vehicle
  • Action: Ensure the engine is cool. Disconnect the battery and drain the coolant into a catch pan.
Step 2: Locate the Thermostat
  • Action: The thermostat on the 2019 Silverado 1500 is typically located at the engine end of the upper radiator hose.
  • Expected Outcome: Remove the hose clamp and detach the upper radiator hose.
Step 3: Remove the Thermostat Housing
  • Action: Unbolt the thermostat housing using the appropriate socket. Carefully lift the housing off to expose the thermostat.
  • Expected Outcome: Remove the old thermostat and inspect the housing for any debris or damage.
Step 4: Install the New Thermostat
  • Action: Place the new thermostat into position, ensuring the orientation matches the old one (usually with the spring side facing the engine).
  • Expected Outcome: Secure the thermostat housing back into place using the bolts. Torque them to manufacturer specifications.
Step 5: Reconnect the Cooling System
  • Action: Reattach the upper radiator hose and secure the clamp. Refill the cooling system with the appropriate coolant mixture.
  • Expected Outcome: Start the engine and allow it to reach operating temperature, checking for leaks.
Step 6: Final Checks
  • Action: Monitor the temperature gauge and check for proper heater operation.
  • Expected Outcome: The vehicle should maintain a stable temperature, and the heater should provide warm air.

By following these detailed steps, you should be able to diagnose and repair a failing thermostat in your 2019 Chevrolet Silverado 1500 effectively.