AutoCodes – Toyota – P0128 2001 Toyota Highlander

P0128 2001 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 2001 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 7,317

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 2001 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 2001 Toyota Highlander - Coolant Thermostat - AutoCodes.com — P0128 2001 Toyota Highlander Code - Coolant Thermostat

What does this mean?

What are the Possible Causes of the DTC P0128 2001 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 2001 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 2001 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 2001 Toyota Highlander code?

Need more information on how to fix the P0128 2001 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 2001 Toyota Highlander Code

1. What does OBDII code P0128 on a 2001 Toyota Highlander indicate?

- This code indicates a problem with the coolant thermostat in the vehicle.

2. What are the common symptoms of a P0128 code in a 2001 Toyota Highlander?

- Common symptoms include the engine running cooler than normal, poor fuel economy, and the Check Engine light being illuminated.

3. What are the possible causes of a P0128 code in a 2001 Toyota Highlander?

- Possible causes include a faulty coolant thermostat, a malfunctioning coolant temperature sensor, low coolant levels, or a stuck open thermostat.

4. How can I diagnose the cause of a P0128 code in my 2001 Toyota Highlander?

- Diagnosis typically involves checking the coolant level, inspecting the thermostat for proper operation, testing the coolant temperature sensor, and verifying the cooling system's overall functionality.

5. Can I continue driving my 2001 Toyota Highlander with a P0128 code?

- It is not recommended to drive with a P0128 code as it can lead to engine overheating and potential damage. It is advised to address the issue promptly.

6. How can I repair a P0128 code in my 2001 Toyota Highlander?

- Repair usually involves replacing the faulty coolant thermostat, ensuring proper coolant levels, and checking for any leaks in the cooling system.

7. Is it possible to reset the Check Engine light after fixing a P0128 code on a 2001 Toyota Highlander?

- Yes, once the underlying issue causing the P0128 code is repaired, the Check Engine light can be reset using an OBDII scanner.

8. Can a DIY enthusiast fix a P0128 code in a 2001 Toyota Highlander?

- Depending on their skill level, a DIY enthusiast may be able to replace the coolant thermostat to address a P0128 code. However, it's recommended to consult a professional if unsure.

9. How much does it typically cost to repair a P0128 code in a 2001 Toyota Highlander?

- The cost of repairing a P0128 code can vary depending on the exact cause of the issue, but it generally ranges from $150 to $300 for parts and labor.

10. Will a P0128 code affect the performance of my 2001 Toyota Highlander?

- Yes, a P0128 code can affect the performance of the vehicle by causing inefficient fuel combustion, potential overheating, and overall reduced engine efficiency.