P0128 code on a Honda Civic: Causes and Fixing

The P0128 code on a Honda Civic indicates a problem with the engine coolant temperature (ECT) sensor circuit. This code is triggered when the ECT sensor is sending a signal that is outside the expected range for normal engine operation.

P0128 code on a Honda Civic

The ECT sensor is responsible for sending a signal to the engine control module (ECM) to help regulate the engine’s operating temperature.

When the ECT sensor fails, it can cause a variety of issues with the engine’s performance, such as reduced fuel efficiency, rough idle, or even stalling.

Here are some possible causes for the P0128 code on a Honda Civic:

1. Faulty ECT sensor: This is the most common cause of the P0128 code. The ECT sensor may be failing, sending a signal that is outside the normal range.
2. Low engine coolant level: If the engine coolant level is low, the ECT sensor may not be able to accurately measure the engine’s temperature.
3. Thermostat stuck open: If the thermostat is stuck open, the engine may not be able to reach its optimal operating temperature, causing the ECT sensor to trigger the P0128 code.
4. Wiring or connection issues: Wiring or connection issues between the ECT sensor and the ECM can cause the P0128 code to be triggered.
5. Failed ECM: In rare cases, the ECM may be malfunctioning, causing the P0128 code to be triggered.

To diagnose and fix the issue, it is recommended to take the car to a certified mechanic who has experience working with Honda Civics.

The mechanic will use a scan tool to read the code and diagnose the problem. They may perform a visual inspection of the wiring and connections, test the ECT sensor, and check the engine coolant level and thermostat. Depending on the cause of the problem, they may replace the ECT sensor, and thermostat, or repair any wiring or connection issues.

P0128 code on a Honda Civic possible causes

Table: P0128 code on a Honda Civic possible causes and comments for them

It’s important to note that there may be other, less common causes of the P0128 code, and a proper diagnosis by a qualified mechanic is recommended to ensure the correct cause is identified and repaired.

P0128 code on a Honda Civic Tech Note

Here are some additional technical notes regarding the P0128 code on a Honda Civic:

• The P0128 code is a common issue with Honda Civics, particularly those manufactured between 2001 and 2006. If you own one of these models and experience this code, it’s likely due to a failing ECT sensor.
• When diagnosing the P0128 code, it’s important to ensure that the engine is fully warmed up before testing the ECT sensor. This is because the sensor may function properly at lower temperatures, but fail once the engine reaches normal operating temperature.
• In some cases, the P0128 code may be accompanied by other codes related to engine temperature or coolant, such as P0117 or P0118. If you experience multiple codes related to engine temperature, it’s likely that there is a more significant issue with the cooling system.
• It’s important to address the P0128 code as soon as possible, as it can cause reduced fuel efficiency and potential damage to the engine if left unchecked. If you’re not comfortable diagnosing and repairing the issue yourself, it’s recommended to take your Honda Civic to a qualified mechanic for proper diagnosis and repair.

P0128 code on a Honda Civic possible symptoms and solutions

Table: P0128 code on a Honda Civic possible symptoms and solutions for them

It’s important to note that the symptoms of the P0128 code can vary depending on the severity of the underlying issue. If you experience any of these symptoms, it’s recommended to take your Honda Civic to a qualified mechanic for proper diagnosis and repair.

P0128 code on a Honda Civic Description

The P0128 code on a Honda Civic is a diagnostic trouble code that indicates an issue with the engine coolant temperature (ECT) sensor circuit.

This code is triggered when the ECT sensor is sending a signal that is outside the expected range for normal engine operation.

The ECT sensor is responsible for measuring the temperature of the engine coolant and sending a signal to the engine control module (ECM) to help regulate the engine’s operating temperature.

When the ECT sensor fails or sends an incorrect signal, it can cause a variety of issues with the engine’s performance, such as reduced fuel efficiency, rough idle, or even stalling.

The P0128 code is typically caused by a faulty ECT sensor, low engine coolant level, a stuck open thermostat, wiring or connection issues between the ECT sensor and the ECM, or a failed ECM.

To diagnose and repair the issue, it is recommended to take the car to a certified mechanic who has experience working with Honda Civics.

The mechanic will use a scan tool to read the code and diagnose the problem, and may perform a visual inspection of the wiring and connections, test the ECT sensor, and check the engine coolant level and thermostat. Depending on the cause of the problem, they may replace the ECT sensor, thermostat, or repair any wiring or connection issues.

How much does it cost to diagnose and fix the P0128 code on a Honda Civic?

The cost to diagnose and fix the P0128 code on a Honda Civic can vary depending on the cause of the problem and the mechanic’s labor rates. Here are some estimated costs:

• Diagnostic scan: A diagnostic scan to read the code and identify the underlying issue can cost anywhere from $50 to $150, depending on the mechanic’s hourly rate and location.
• ECT sensor replacement: If the ECT sensor is the cause of the P0128 code, replacement parts can range from $20 to $100, depending on the quality of the sensor and where it’s purchased. Labor costs for this repair can range from $50 to $150.
• Thermostat replacement: If the thermostat is stuck open, replacement parts can range from $20 to $50, depending on the quality of the part and where it’s purchased. Labor costs for this repair can range from $100 to $200.
• Wiring or connection repair: If the issue is related to wiring or connection issues between the ECT sensor and the ECM, the cost to repair can vary depending on the location of the issue and the amount of labor required. Expect to pay anywhere from $50 to $200 for this type of repair.
• ECM replacement: In rare cases where the ECM is malfunctioning, replacement parts can range from $500 to $1,500, depending on the model and where it’s purchased. Labor costs for this repair can range from $100 to $500.

Overall, the total cost to diagnose and fix the P0128 code on a Honda Civic can range from $100 to $1,500, depending on the cause of the problem and the mechanic’s labor rates. It’s recommended to get a quote from a qualified mechanic before authorizing any repairs to ensure that you’re getting a fair price for the work.

How to fix the P0128 code on a Honda Civic?

To fix the P0128 code on a Honda Civic, you will need to diagnose the underlying issue and repair or replace the necessary parts. Here are some steps you can take:

1. Check the engine coolant level: Make sure the engine coolant level is at the appropriate level. If it is low, add more coolant and recheck the code.
2. Check the thermostat: Make sure the thermostat is functioning properly and opening and closing as it should. If it is stuck open, it may need to be replaced.
3. Inspect wiring and connections: Check the wiring and connections between the ECT sensor and the ECM. Make sure they are clean and properly connected. Repair or replace any damaged wiring.
4. Test the ECT sensor: Use a multimeter to test the ECT sensor’s resistance and make sure it’s within the manufacturer’s specifications. If it’s outside the range, it may need to be replaced.
5. Replace the ECT sensor: If the ECT sensor is the cause of the P0128 code, replace it with a new one. Make sure it is the correct part for your Honda Civic.
6. Clear the code: Use a scan tool to clear the P0128 code from the ECM.
7. Test drive: Take the car for a test drive to ensure the issue has been resolved and the check engine light does not come back on.

If you’re not comfortable diagnosing or repairing the issue yourself, it’s recommended to take your Honda Civic to a qualified mechanic for proper diagnosis and repair.

Takeaways

Here are some takeaways regarding the P0128 code on a Honda Civic:

• The P0128 code indicates an issue with the engine coolant temperature (ECT) sensor circuit.
• The ECT sensor is responsible for measuring the engine coolant temperature and sending a signal to the engine control module (ECM).
• The P0128 code can be caused by a faulty ECT sensor, low engine coolant level, a stuck open thermostat, wiring or connection issues, or a failed ECM.
• Symptoms of the P0128 code may include reduced fuel efficiency, rough idle or stalling, overheating, or poor performance.
• Diagnosing and repairing the issue may involve checking the engine coolant level and thermostat, inspecting wiring and connections, testing the ECT sensor, and potentially replacing the sensor, thermostat, or ECM.
• The cost to diagnose and fix the P0128 code can vary depending on the cause of the problem and the mechanic’s labor rates.
• It’s recommended to take your Honda Civic to a qualified mechanic for proper diagnosis and repair if you’re not comfortable diagnosing or repairing the issue yourself.

Other Honda Civic Codes you Might Want to Check