Engine-CodesGMC – P1258 2015 GMC Sierra

P1258 2015 GMC Sierra Code - Engine Coolant Overtemperature Protection Mode Active

Quick Answer

When the diagnostic trouble code P1258 appears on a 2015 GMC Sierra, it indicates that the Engine Coolant Overtemperature Protection Mode is active. Common causes include Low coolant level or coolant leak, Faulty thermostat, Malfunctioning cooling fan. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1258 2015 GMC Sierra indicates Engine Coolant Overtemperature Protection Mode Active.
Common causes
Common causes include Low coolant level or coolant leak, Faulty thermostat, Malfunctioning cooling fan.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Table of contents Created and updated by William Orellana on Sep 17, 2024
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Code P1258 2015 GMC Sierra Description

When the diagnostic trouble code P1258 appears on a 2015 GMC Sierra, it indicates that the Engine Coolant Overtemperature Protection Mode is active. This means that the engine coolant temperature has exceeded safe operating limits, triggering the vehicle's computer to limit engine power to prevent damage. This protection mode is designed to safeguard the engine from overheating and potential catastrophic failure.

OBDII Code P1258 2015 GMC Sierra - Engine Coolant Overtemperature Protection Mode Active
P1258 2015 GMC Sierra Code - Engine Coolant Overtemperature Protection Mode Active

Common Causes of P1258 2015 GMC Sierra

  1. Low coolant level or coolant leak.
  2. Faulty thermostat.
  3. Malfunctioning cooling fan.
  4. Clogged radiator or cooling system.
  5. Faulty coolant temperature sensor.

Symptoms of P1258 2015 GMC Sierra

  1. Engine overheating warning light illuminated on the dashboard.
  2. Reduced engine power and acceleration.
  3. Engine running hotter than usual.
  4. Engine stalling or running rough.
  5. Increased coolant consumption.

How to Fix P1258 2015 GMC Sierra

  1. Check and top up coolant level: Inspect the coolant reservoir and radiator for proper coolant levels. If low, top up with the recommended coolant type.
  2. Test and replace thermostat: Check the thermostat for proper operation and replace if necessary to ensure proper engine cooling.
  3. Inspect and repair cooling fan: Test the cooling fan operation and replace if not functioning correctly to prevent overheating.
  4. Flush and refill cooling system: Flush the cooling system to remove any debris or contaminants and refill with fresh coolant.
  5. Check and replace coolant temperature sensor: Test the coolant temperature sensor for accuracy and replace if faulty to ensure proper engine temperature monitoring.

Cost to Fix P1258 2015 GMC Sierra

The cost of repairing the Engine Coolant Overtemperature Protection Mode issue on a 2015 GMC Sierra can vary depending on the specific cause of the problem. On average, the repair costs can range from $150 to $500, including parts and labor. It's important to note that diagnostic time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate based on your location and vehicle specifics.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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