AutoCodes – Chevrolet – P0128 2015 Chevrolet Silverado

P0128 2015 Chevrolet Silverado Code - Engine Coolant Temperature Below Thermostat Regulating Temperature

Quick Answer

The Engine Control Module (ECM) monitors the temperature of the engine coolant for engine control and as enabling criteria for some diagnostics. Common causes include Leaking or stuck open thermostat, Low engine coolant level, Insufficient warm-up time. 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: P0128 2015 Chevrolet Silverado indicates Engine Coolant Temperature Below Thermostat Regulating Temperature.
Common causes: Common causes include Leaking or stuck open thermostat, Low engine coolant level, Insufficient warm-up time.
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 1,382

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

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Table of contents Created and updated by William Orellana on May 11, 2023

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0128 2015 Chevrolet Silverado Description

The Engine Control Module (ECM) monitors the temperature of the engine coolant for engine control and as enabling criteria for some diagnostics. The amount of heat an engine generates is proportional to the amount of air that enters the engine. The ECM monitors this amount of air to calculate a theoretical Engine Coolant Temperature (ECT). The ECM uses the calculated temperature to determine if the engine has warmed up to the thermostat regulating temperature. Suppose the measured actual coolant temperature does not increase typically or does not reach the thermostat regulating temperature. In that case, diagnostics that use the ECT as enabling criteria, may not run when expected. If the measured engine coolant temperature fails to reach the thermostat regulating temperature, before a predetermined amount of air has entered the engine, this Diagnostic Trouble Code (DTC) sets.

OBDII Code P0128 2015 Chevrolet Silverado - Engine Coolant Temperature Below Thermostat Regulating Temperature - AutoCodes.com — P0128 2015 Chevrolet Silverado Code - Engine Coolant Temperature Below Thermostat Regulating Temperature

What does this mean?

What are the Possible Causes of the DTC P0128 2015 Chevrolet Silverado?

Leaking or stuck open thermostat
Low engine coolant level
Insufficient warm-up time
Faulty Engine Coolant Temperature (ECT) sensor
Engine Coolant Temperature sensor harness is open or shorted
Engine Coolant Temperature sensor electrical circuit poor connection

How to Fix the DTC P0128 2015 Chevrolet Silverado?

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 does this mean?

Code Tech Notes

If the cooling system is not leaking and the fluid level is OK, replacing the thermostat usually takes care of the problem.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0128 2015 Chevrolet Silverado 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.

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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 P0128 2015 Chevrolet Silverado Code

What does the OBDII code P0128 mean on a 2015 Chevrolet Silverado?

1. P0128 indicates that the engine coolant temperature is not reaching the thermostat's regulating temperature within the expected time. 2.

What are the common symptoms of code P0128 in a 2015 Chevrolet Silverado?

Symptoms may include poor fuel efficiency, the engine taking longer to warm up, the heater not operating effectively, and the check engine light turning on. 3.

What are the most likely causes of a P0128 code on a 2015 Chevrolet Silverado?

Common causes include a stuck-open thermostat, a faulty coolant temperature sensor, low coolant levels, or issues with the engine cooling system. 4.

Can a stuck-open thermostat trigger a P0128 code?

Yes, a thermostat stuck in the open position may prevent the engine from reaching its optimal temperature, causing the P0128 code to appear. 5.

How do I fix the P0128 code on my 2015 Chevrolet Silverado?

Repairs typically involve replacing the thermostat, inspecting and replacing the coolant temperature sensor if faulty, checking coolant levels, and ensuring the cooling system is functioning properly. 6.

Is it safe to drive a 2015 Chevrolet Silverado with a P0128 code?

While the vehicle may still be drivable, prolonged driving with this code can result in reduced fuel efficiency and potential long-term engine wear due to improper operating temperatures. 7.

How much does it cost to repair a P0128 code on a 2015 Chevrolet Silverado?

Repair costs can vary but typically range from $150 to $300 for parts and labor to replace the thermostat or coolant temperature sensor. 8.

Can a bad coolant temperature sensor cause a P0128 code?

Yes, a malfunctioning coolant temperature sensor can send incorrect data to the engine control module, triggering the P0128 code. 9.

Will clearing the P0128 code fix the issue on a 2015 Chevrolet Silverado?

Clearing the code will reset the check engine light temporarily, but the underlying issue must be resolved to prevent the code from returning. 10.

How can I diagnose the P0128 code on a 2015 Chevrolet Silverado?

Use an OBDII scanner to confirm the code, check the coolant level, inspect the thermostat for proper operation, and test the coolant temperature sensor for accuracy.