AutoCodes – Toyota – P0128 2002 Toyota Highlander

P0128 2002 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 2002 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 8,304

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 2002 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 2002 Toyota Highlander - Coolant Thermostat - AutoCodes.com — P0128 2002 Toyota Highlander Code - Coolant Thermostat

What does this mean?

What are the Possible Causes of the DTC P0128 2002 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 2002 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 2002 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 2002 Toyota Highlander code?

Need more information on how to fix the P0128 2002 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 2002 Toyota Highlander Code

1. What does OBDII code P0128 mean on a 2002 Toyota Highlander?

- OBDII code P0128 on a 2002 Toyota Highlander indicates a problem with the coolant thermostat.

2. What are the common symptoms of a P0128 code on a 2002 Toyota Highlander?

- Common symptoms of a P0128 code include the temperature gauge reading lower than normal, poor fuel economy, and the Check Engine light being illuminated.

3. What are the possible causes of a P0128 code on a 2002 Toyota Highlander?

- The P0128 code on a 2002 Toyota Highlander is commonly caused by a faulty thermostat, low coolant level, a malfunctioning engine coolant temperature sensor, or a stuck-open thermostat.

4. How can I diagnose the P0128 code on my 2002 Toyota Highlander?

- To diagnose the P0128 code, you can start by checking the coolant level, inspecting the thermostat for proper operation, and testing the engine coolant temperature sensor.

5. Can I continue driving my 2002 Toyota Highlander with a P0128 code?

- It is not recommended to continue driving your 2002 Toyota Highlander with a P0128 code as it can lead to engine overheating and potential damage.

6. How do I repair a P0128 code on my 2002 Toyota Highlander?

- To repair a P0128 code on a 2002 Toyota Highlander, you may need to replace the coolant thermostat, refill the coolant system, and clear the code using an OBDII scanner.

7. Is it possible to reset the P0128 code on a 2002 Toyota Highlander without fixing the issue?

- While you can clear the P0128 code using an OBDII scanner, it is not recommended to reset the code without addressing the underlying issue to prevent potential engine damage.

8. How much does it cost to fix a P0128 code on a 2002 Toyota Highlander?

- The cost of fixing a P0128 code on a 2002 Toyota Highlander can vary depending on the exact cause of the issue, but it typically ranges from $150 to $300 for parts and labor.

9. Will a P0128 code on my 2002 Toyota Highlander affect the vehicle's performance?

- Yes, a P0128 code can affect the performance of your 2002 Toyota Highlander by causing issues such as reduced fuel efficiency and potential engine overheating.

10. How often should the coolant thermostat be replaced in a 2002 Toyota Highlander?

- The coolant thermostat in a 2002 Toyota Highlander should be replaced as part of regular maintenance or when symptoms of a faulty thermostat, like a P0128 code, are detected.