What is the code P0128 on a Dodge Dart?

The Dodge Dart code P0128 is a diagnostic trouble code that indicates an issue with the engine's coolant temperature. This code is triggered when the engine coolant temperature does not reach the expected operating temperature within a specified time frame after the engine is started.

What is the Dodge Dart Code P0128?

The Dodge Dart code P0128 is a diagnostic trouble code that is set when the engine coolant temperature does not reach the expected operating temperature within a specified time after the engine is started. This code is related to the engine's cooling system and can indicate a problem with the thermostat, coolant temperature sensor, or other components in the cooling system.

When the engine is started, the coolant temperature should rise to the normal operating temperature within a certain amount of time. If the coolant temperature does not reach this threshold, the P0128 code will be set by the vehicle's onboard computer, indicating that there is an issue with the engine's cooling system.

Possible Causes of the P0128 Code

There are several potential causes for the Dodge Dart code P0128, including:

• Faulty thermostat: The thermostat is responsible for regulating the flow of coolant through the engine, and a stuck-open or faulty thermostat can prevent the engine from reaching the proper operating temperature.


• Coolant temperature sensor issue: The coolant temperature sensor provides information to the vehicle's computer about the temperature of the coolant. If this sensor is malfunctioning, it can cause the P0128 code to be set.


• Coolant system leaks: If there are any leaks in the coolant system, it can prevent the engine from reaching the proper operating temperature, triggering the P0128 code.


• Blocked or restricted coolant flow: If there is a blockage or restriction in the coolant system, it can prevent the engine from reaching the proper operating temperature, leading to the P0128 code.

If you receive the Dodge Dart code P0128, it's important to have the vehicle diagnosed by a qualified mechanic to determine the root cause of the issue and make the necessary repairs.

How serious is the P0128 engine code?

Driving with a P0128 error code for a short distance is generally safe, but it's not a good idea to ignore the issue for an extended period. While your vehicle might still operate, it's likely to experience reduced fuel efficiency and potentially more serious mechanical issues over time.

What is the code P0128 on a 2013 Dodge Dart?

The P0128 code on a 2013 Dodge Dart means the engine is running cooler than it should, indicating a problem with the engine coolant temperature. The most common cause is a faulty thermostat stuck open, but other possibilities include a low coolant level or a defective coolant temperature sensor. 
This video explains what P0128 code is and how to troubleshoot it: 58s8020 AutomotiveYouTube · Jan 28, 2024
Common causes

• Thermostat stuck open: This is the most frequent reason for a P0128 code. The thermostat fails to close properly, allowing too much coolant to flow and preventing the engine from reaching its optimal operating temperature. 
• Low coolant level: A low coolant level can create an air pocket near the temperature sensor, causing inaccurate readings. It can also be a symptom of a leak, which prevents the system from building enough pressure to heat up properly. 
• Defective coolant temperature sensor (ECT): The sensor may be providing incorrect information to the engine control module (ECM), even if the engine's temperature is actually normal. 
• Defective coolant fan: If the cooling fan is running too often, it can overcool the engine, especially in colder weather. 

This video shows how to replace a faulty thermostat: 49sMopar MotorsportsYouTube · Nov 21, 2021
What to do

1. Check the coolant level: First, check the engine coolant level in the reservoir when the engine is cold and top it off if it's low. 
2. Inspect for leaks: Look for any signs of coolant leaks around the hoses, radiator, or water pump. 
3. Replace the thermostat: If the coolant level is good and there are no leaks, the thermostat is the most likely culprit and should be replaced. This is the most common fix for this code. 
4. Consider the ECT sensor: If replacing the thermostat doesn't solve the problem, the coolant temperature sensor may need to be tested and replaced. 

How do I know if my thermostat or temperature sensor is bad?

Common Signs of Faulty Temperature Sensors

1. Erratic or jumpy readings.
2. Very high temperature (open circuit)
3. Negative/very low temperature (short circuit)
4. Gradual drift.
5. Noise or interference.
6. Physical wire damage.

How do I fix the engine code P0128?

To fix a P0128 code, first check and correct the coolant level, as low coolant is a common cause. If that doesn't resolve the issue, the most common fix is to replace the thermostat, as it is likely stuck open. If a new thermostat doesn't work, further steps include checking the coolant temperature sensor and its wiring for damage. 
Steps to fix the P0128 code
This video demonstrates how to replace a thermostat and fix a P0128 code: 55snondaYouTube · Oct 27, 2020

1. Check and top off the coolant: Ensure the engine is cool, then check the coolant level in the reservoir. Add the correct type of coolant if it is low. 
2. Inspect for leaks: Look for any visible signs of leaks in the cooling system hoses and around the radiator cap. 
3. Replace the thermostat: This is the most common fix for a P0128 code. A thermostat that is stuck open will prevent the engine from reaching its proper operating temperature. 
4. Inspect the coolant temperature sensor (ECT): If replacing the thermostat doesn't solve the problem, the ECT sensor itself or its wiring could be faulty. 
5. Check the wiring and connections: Inspect the wiring connected to the ECT sensor for any damage, corrosion, or loose connections. Repair or replace any damaged sections. 
6. Clear the code: Use an OBD-II scanner to clear the P0128 code from the vehicle's computer. 
7. Test drive the vehicle: Drive the car for a period to see if the engine reaches its proper operating temperature and if the code returns.