AutoCodes – Toyota – P0128 2007 Toyota Highlander

P0128 2007 Toyota Highlander Code - Coolant Thermostat

Quick Answer

Coolant temperature below thermostat regulating temperature. 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 2007 Toyota Highlander indicates Coolant Thermostat.
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 6,828

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 Apr 21, 2019

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0128 2007 Toyota Highlander Description

Coolant temperature below thermostat regulating temperature. 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 2007 Toyota Highlander - Coolant Thermostat - AutoCodes.com — P0128 2007 Toyota Highlander Code - Coolant Thermostat

What does this mean?

What are the Possible Causes of the DTC P0128 2007 Toyota Highlander?

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 2007 Toyota Highlander?

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 2007 Toyota Highlander 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 2007 Toyota Highlander code?

Need more information on how to fix the P0128 2007 Toyota Highlander 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 P0128 2007 Toyota Highlander Code

1. What does OBDII code P0128 on a 2007 Toyota Highlander indicate?

The code P0128 in a 2007 Toyota Highlander typically indicates an issue with the coolant thermostat.

2. What are the common symptoms of a P0128 code in a Toyota Highlander?

Common symptoms of a P0128 code may include the engine running colder than normal, poor fuel economy, and the check engine light being illuminated.

3. What causes the P0128 code to trigger in a 2007 Toyota Highlander?

The P0128 code in a Toyota Highlander is often triggered by a thermostat that is stuck open or is not functioning properly, leading to inefficient engine temperature regulation.

4. How can I diagnose a P0128 code in my 2007 Toyota Highlander?

To diagnose a P0128 code, it is recommended to check the coolant level, test the thermostat operation, inspect for leaks, and verify the engine temperature sensor readings.

5. Can I continue driving my 2007 Toyota Highlander with a P0128 code?

It is not recommended to continue driving with a P0128 code, as it can lead to decreased fuel efficiency and potential damage to the engine due to improper temperature regulation.

6. How do I repair a P0128 code in my Toyota Highlander?

Repairing a P0128 code typically involves replacing the coolant thermostat, ensuring proper coolant levels, and clearing the error code using an OBDII scanner.

7. What are the consequences of ignoring a P0128 code in a 2007 Toyota Highlander?

Ignoring a P0128 code can result in reduced engine performance, decreased fuel efficiency, potential overheating, and long-term damage to engine components.

8. Is it possible to reset a P0128 code in a Toyota Highlander without fixing the issue?

While it is possible to clear the error code temporarily, it is essential to address the underlying problem causing the P0128 code to prevent further issues.

9. How much does it cost to repair a P0128 code in a 2007 Toyota Highlander?

The cost of repairing a P0128 code in a Toyota Highlander can vary depending on the labor rates and the price of parts, but it typically ranges from $150 to $300.

10. Can a DIY enthusiast fix a P0128 code in a Toyota Highlander?

Depending on your skill level, replacing a coolant thermostat to fix a P0128 code in a Toyota Highlander can be a manageable DIY project with the right tools and guidance.