AutoCodes – GMC – P1258 2016 GMC Sierra

P1258 2016 GMC Sierra Code - Engine Coolant Overtemperature Protection Mode Active

Quick Answer

The Engine Control Module (ECM) uses the Engine Coolant Temperature (ECT) sensor to monitor the engine for an over-temperature condition. Common causes include Low Engine Coolant, Faulty Thermostat, Faulty Engine Coolant Temperature Sensor. 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 2016 GMC Sierra indicates Engine Coolant Overtemperature Protection Mode Active.
Common causes: Common causes include Low Engine Coolant, Faulty Thermostat, Faulty Engine Coolant Temperature Sensor.
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.

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Code Popularity 203

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 13, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1258 2016 GMC Sierra Description

The Engine Control Module (ECM) uses the Engine Coolant Temperature (ECT) sensor to monitor the engine for an over-temperature condition. This condition occurs when the coolant temperature is above a calibrated value for a calibrated length of time. The ECM will disable half of the cylinders by turning OFF the fuel injectors. By disabling half of the cylinders, the ECM is able to reduce the temperature of the coolant. The Diagnostic Trouble Code (DTC) will be set when the coolant temperature is warmer than 129°C (264°F) for greater than 10 seconds.

OBDII Code P1258 2016 GMC Sierra - Engine Coolant Overtemperature Protection Mode Active - AutoCodes.com — P1258 2016 GMC Sierra Code - Engine Coolant Overtemperature Protection Mode Active

What does this mean?

What are the Possible Causes of the DTC P1258 2016 GMC Sierra?

Low Engine Coolant
Faulty Thermostat
Faulty Engine Coolant Temperature Sensor
Engine Coolant Temperature Sensor harness is open or shorted
Engine Coolant Temperature Sensor circuit poor electrical connection

How to Fix the DTC P1258 2016 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1258 2016 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P1258 2016 GMC Sierra code?

Need more information on how to fix the P1258 2016 GMC Sierra code? Get Access to Factory Service Manuals

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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.

Frequently Asked Questions about P1258 2016 GMC Sierra Code

1. What does the OBDII code P1258 mean on a 2016 GMC Sierra?

P1258 indicates that the Engine Coolant Overtemperature Protection Mode has been activated due to excessively high engine coolant temperatures.

2. What are the common symptoms of code P1258 on a 2016 GMC Sierra?

Symptoms include reduced engine power, high coolant temperature readings, the engine entering protection mode, and possible dashboard warning lights.

3. What causes code P1258 on a 2016 GMC Sierra?

Common causes include low coolant levels, a stuck thermostat, a malfunctioning water pump, a faulty radiator fan, or a clogged radiator.

4. Can I drive my 2016 GMC Sierra with code P1258 active?

It’s not recommended to drive the vehicle, as continued operation with high coolant temperatures can cause severe engine damage, such as a blown head gasket.

5. How do I fix code P1258 on a 2016 GMC Sierra?

Check and refill coolant if low, inspect for leaks, replace the thermostat if stuck, ensure the radiator fan is functioning, and clean or replace a clogged radiator.

6. How does the Engine Coolant Overtemperature Protection Mode work on a GMC Sierra?

The protection mode reduces engine power to prevent overheating and minimize the risk of severe engine damage.

7. What tools do I need to diagnose code P1258 on a 2016 GMC Sierra?

You may need an OBDII scanner, a coolant pressure tester, and basic automotive tools to inspect components like the thermostat, radiator, and water pump.

8. Can a bad temperature sensor cause code P1258 on a 2016 GMC Sierra?

Yes, a faulty coolant temperature sensor can send incorrect readings to the engine control module, triggering the code.

9. How much does it cost to repair code P1258 on a 2016 GMC Sierra?

Repair costs vary depending on the cause but can range from $50 for a thermostat replacement to several hundred dollars for a water pump or radiator repair.

10. How can I prevent code P1258 on my 2016 GMC Sierra?

Regularly check coolant levels, inspect for leaks, ensure proper maintenance of the cooling system, and replace worn components as needed.