The OBD code P0128 indicates a problem with the Engine Coolant Temperature (ECT) sensor circuit.
This code affects the engine cooling system.
Symptoms include the Check Engine Light being illuminated.
Causes can be a leaking or stuck open thermostat, low coolant level, or a faulty ECT sensor.
It is important to address this issue promptly to prevent engine damage.
A possible fix is to inspect the thermostat, coolant level, and ECT sensor for any issues.
| Repair Importance Level | 10.0 (Out of 10) |
| Estimated Repair Time | Approximately 1.0 hour |
| Repair Difficulty Level | 6.67 (Out of 10) |
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Symptoms of the p0128 OBD Code
The vehicle may show a lower than expected coolant temperature, triggering fault code P0128.
- Symptoms: Engine Light ON.
- Temperature gauge reading lower than normal.
- Coolant level may be low.
- Heater may not produce hot air.
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Causes of the p0128 OBD Code
P0128 is typically triggered by a thermostat stuck open or a faulty coolant temperature sensor.
- P0128 can be caused by a leaking or stuck open thermostat.
- Low engine coolant level.
- Insufficient warmup time.
- A faulty Engine Coolant Temperature (ECT) sensor.
- An Engine Coolant Temperature sensor harness that is open or shorted.
- An Engine Coolant Temperature sensor electrical circuit with a poor connection.
Fixing Error Code p0128 Step By Step
Addressing fault code P0128 involves diagnosing and resolving issues related to the coolant thermostat.
- To fix OBDII code P0128, first, review the ‘Possible Causes’ mentioned above and visually examine the corresponding wiring harness and connectors.
- Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.
- Next, check the engine coolant level and quality to ensure it meets the manufacturer’s specifications.
- If the coolant is low or degraded, top it up or replace it accordingly.
- Then, inspect the thermostat for proper operation; if it’s faulty, replace it.
- Finally, clear the fault code using a scan tool and test drive the vehicle to verify that the code does not return.
Cost Of Fixing p0128 Fault Code
Diagnosing and repairing fault code P0128 typically involves checking the thermostat and coolant temperature sensor.
The cost to diagnose and fix OBD code P0128 typically ranges from $75 to $150, based on a 1. 0hour repair time.
Factors like shop rates and complexity can affect the final cost.
Details of the p0128 OBD Code
P0128 indicates the engine coolant temperature is below the thermostat regulating temperature.
OBD code P0128 means that the engine coolant temperature is below the thermostat regulating temperature.
This code is triggered by the Engine Control Module (ECM) when the temperature reading from the coolant sensor does not increase to the expected level within a specified time after starting the engine.
The P0128 code is related to the engine coolant system.
It indicates that the engine is not reaching operating temperature within a specified time frame after starting.
This could be caused by a faulty thermostat, a malfunctioning coolant temperature sensor, a low coolant level, or a problem with the cooling system.
Mechanic’s Tech Notes
Code P0128 indicates a fault in the engine coolant temperature sensor or thermostat.
To diagnose and fix OBDII code P0128 (Coolant Thermostat Malfunction), start by checking the coolant level and quality.
Use a voltmeter to test the thermostat and coolant temperature sensor.
Verify proper operation of the thermostat by monitoring the engine temperature with a scan tool.
Inspect the wiring harness and connectors for any damage or corrosion.
Ensure the thermostat is closing properly when the engine reaches operating temperature.
If necessary, replace the thermostat and clear the fault code.
Remember to perform a test drive to confirm the repair.
FAQ
Common causes of OBD code P0128 include a leaking or stuck open thermostat, low engine coolant level, insufficient warmup time, faulty ECT sensor, or related wiring issues.
OBD code P0128 indicates a potential issue with the engine coolant temperature. It’s recommended to address it promptly to prevent engine damage. Avoid driving long distances.
To diagnose and repair OBD code P0128, check for a leaking thermostat, low coolant, faulty ECT sensor, or wiring issues. Inspect wiring and connectors for damage or corrosion.
Wrap Up
If your check engine light is on and your engine is not reaching operating temperature, you may be dealing with OBDII code P0128. This code typically indicates a problem with the thermostat, coolant temperature sensor, or low coolant level.
Faulty sensors, a stuckopen thermostat, or wiring issues could be causing this code.
To address OBDII code P0128, start by checking the coolant level and quality.
Inspect the thermostat for proper operation and the coolant temperature sensor for any signs of damage.
Test the sensor’s resistance and ensure the wiring harness and connectors are in good condition to
