Engine-Codes.com
Engine-Codes – Dodge – P0128 Dodge

P0128 Dodge Code - Thermostat Rationality

Quick Answer

The P0128 diagnostic trouble code (DTC) for Dodge vehicles refers to "Thermostat Rationality." This code is typically triggered when the engine's coolant temperature does not rise to the expected level within a specified time after starting the vehicle. Common causes include Faulty thermostat, Low coolant level, Defective coolant temperature sensor. 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 Dodge indicates Thermostat Rationality.
Common causes
Common causes include Faulty thermostat, Low coolant level, Defective coolant temperature sensor.
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.
What is this?
Table of contents Created and updated by William Orellana on Aug 30, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0128 Dodge Description

The P0128 diagnostic trouble code (DTC) for Dodge vehicles refers to "Thermostat Rationality." This code is typically triggered when the engine's coolant temperature does not rise to the expected level within a specified time after starting the vehicle. The thermostat is a crucial component of the engine cooling system that regulates the flow of coolant to maintain optimal operating temperature. When the thermostat fails to function properly, it can impact the vehicle's performance, fuel efficiency, and emissions.

OBDII Code P0128 Dodge - Thermostat Rationality
P0128 Dodge Code - Thermostat Rationality

Common Causes of P0128 Dodge

  1. Faulty thermostat
  2. Low coolant level
  3. Defective coolant temperature sensor
  4. Clogged radiator
  5. Malfunctioning water pump

Symptoms of P0128 Dodge

  1. Engine running colder than normal
  2. Decreased fuel efficiency
  3. Check Engine Light illuminated
  4. Poor heater performance
  5. Overheating in extreme cases

How to Fix P0128 Dodge

  1. Diagnostic testing to confirm P0128 code and identify the root cause
  2. Inspect thermostat, coolant level, sensor, radiator, and water pump
  3. Replace thermostat if found faulty
  4. Flush and refill coolant system
  5. Clear DTC and perform test drive to ensure issue is resolved

Cost to Fix P0128 Dodge

The cost of repairing a P0128 code in a Dodge vehicle can vary depending on the extent of the issue and the specific components that need replacement. On average, the repair cost for this code can range from $150 to $400, including parts and labor. It's important to note that prices may differ based on the location of the repair shop, the make and model of the vehicle, and the type of engine. Additionally, labor rates can fluctuate between different auto repair facilities, with hourly rates typically ranging between $80 and $150. For an accurate estimate, it is recommended to consult with local repair shops.

What does this mean?

Tech Notes for P0128 Dodge

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

When is the Code Detected?

Coolant temperature does not reach predicted engine coolant temperature within specific time

Need more information about the P0128 Dodge code?

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

Need Help with the Code?

Get the P0128 Dodge 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 Dodge Code

1. What are the common symptoms of OBDII code P0128 in a Dodge vehicle?

The common symptoms of code P0128 in a Dodge vehicle include the engine running cooler than normal, decreased fuel efficiency, and the check engine light being illuminated.

2. What is the main cause of OBDII code P0128 in a Dodge?

The main cause of code P0128 in a Dodge is typically a malfunctioning thermostat that is stuck open or opening too soon.

3. How does a malfunctioning thermostat trigger OBDII code P0128 in a Dodge?

When the thermostat is stuck open or opening too soon, the engine is unable to reach its optimal operating temperature, triggering the code P0128 to indicate that the thermostat is not functioning correctly.

4. Can a faulty coolant temperature sensor cause OBDII code P0128 in a Dodge?

Yes, a faulty coolant temperature sensor can potentially cause code P0128 in a Dodge by providing incorrect temperature readings to the engine control module.

5. What are some repair tips for resolving OBDII code P0128 in a Dodge?

Repair tips for resolving code P0128 in a Dodge include replacing the thermostat with a high-quality part, ensuring proper coolant levels and mixture, and checking for any leaks in the cooling system.

6. Is it safe to continue driving a Dodge with OBDII code P0128?

It is not recommended to continue driving a Dodge with code P0128 for an extended period, as it can lead to potential engine damage and decreased fuel efficiency.

7. How can I reset OBDII code P0128 in a Dodge after making repairs?

After making the necessary repairs to resolve code P0128 in a Dodge, the code can be reset using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes.

8. Are there any preventive maintenance measures to avoid OBDII code P0128 in a Dodge?

To prevent OBDII code P0128 in a Dodge, regular maintenance of the cooling system, including thermostat inspection and replacement as needed, is essential.

9. Can extreme weather conditions affect the triggering of OBDII code P0128 in a Dodge?

Extreme weather conditions, such as very cold temperatures, can potentially exacerbate the issues related to a malfunctioning thermostat and lead to the triggering of code P0128 in a Dodge.

10. How long does it typically take to repair OBDII code P0128 in a Dodge?

The repair time for OBDII code P0128 in a Dodge can vary depending on the exact cause of the issue, but it generally takes around 1-2 hours for a professional mechanic to diagnose and fix the problem.

Discuss the causes and fixes for P0128 Dodge OBDII Code

Submit a New Comment

  • I recently replaced exuast manifold gasket and engine light came on and between 40&50 miles per hour it gets a shaking rough ride until the gas pedal is pushed down then it goes away

    Reply to Comment

  • What model and year is your vehicle?

    Reply to Comment