AutoCodes – Isuzu – P0128 Isuzu

P0128 Isuzu Code - Engine Coolant Temperature Below Thermostat Regulating Temperature

Quick Answer

Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine. 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 Isuzu 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 21,363

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

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

Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine.

OBDII Code P0128 Isuzu - Engine Coolant Temperature Below Thermostat Regulating Temperature - AutoCodes.com — P0128 Isuzu Code - Engine Coolant Temperature Below Thermostat Regulating Temperature

What does this mean?

What are the Possible Causes of the DTC P0128 Isuzu?

Leaking or stuck open thermostat
Low engine coolant level
Insufficient warm up time
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 P0128 Isuzu?

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0128 Isuzu 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 P0128 Isuzu code?

Need more information on how to fix the P0128 Isuzu code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0128 Isuzu code diagnosed by a professional: Find a repair shop in your area

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 Isuzu Code

1. What are common symptoms of an OBDII code P0128 on an Isuzu vehicle?

- Common symptoms include the engine temperature gauge reading lower than normal, a dashboard warning light illuminating, poor fuel economy, and decreased heater performance.

2. What does the OBDII code P0128 on an Isuzu indicate?

- The code indicates that the engine coolant temperature is below the thermostat regulating temperature for a specified period.

3. What are the possible causes of an OBDII code P0128 on an Isuzu?

- Possible causes include a faulty thermostat, a malfunctioning engine coolant temperature sensor, low coolant levels, a stuck open thermostat, or a problem with the cooling system.

4. How can I diagnose the cause of an OBDII code P0128 on my Isuzu?

- Diagnosis typically involves checking the coolant level, testing the thermostat for proper operation, inspecting the coolant temperature sensor, and ensuring the cooling system is functioning correctly.

5. Can I continue driving my Isuzu with an OBDII code P0128?

- It is not recommended to continue driving with the code unresolved, as it can lead to potential engine damage or overheating issues.

6. How can I repair an OBDII code P0128 on my Isuzu?

- Repair steps may include replacing the thermostat, replacing the engine coolant temperature sensor, flushing and refilling the cooling system, or addressing any other underlying issues identified during diagnosis.

7. Are there any DIY tips for resolving an OBDII code P0128 on an Isuzu?

- DIY tips may include checking and topping up coolant levels, visually inspecting the thermostat for signs of malfunction, and ensuring proper coolant circulation in the system.

8. Is it possible for a loose or damaged radiator cap to trigger an OBDII code P0128 on an Isuzu?

- Yes, a faulty or improperly sealed radiator cap can lead to loss of coolant pressure, affecting the engine's ability to reach and maintain the proper operating temperature.

9. Can extreme weather conditions contribute to triggering an OBDII code P0128 on an Isuzu?

- Yes, extreme cold weather can impact the engine's ability to reach optimal operating temperature, potentially triggering the code.

10. How often should I check my Isuzu's cooling system to prevent an OBDII code P0128 from occurring?

- It is recommended to check the cooling system during routine maintenance intervals or if you notice any irregularities in engine temperature or performance. Regular checks can help prevent issues that may lead to the code being triggered.