P0128 - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125
In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle.
Symptoms: You will likely not notice any drivability problems other than the MIL illumination.
Causes: A code P0128 may mean that one or more of the following has happened:
* Low engine coolant level
* Leaking or stuck open thermostat
* Faulty cooling fan (running too much)
* Faulty coolant temperature (ECT) sensor
* Faulty intake air temperature (IAT) sensor
Possible Solutions: Past experience indicates that the most likely solution is to replace the thermostat. However here are some suggestions on troubleshooting and repairing a P0128 OBD-II code:
* Verify coolant strength & level
* Verify proper cooling fan operation (check if it's running more than it should). Replace if necessary.
* Verify proper engine coolant temperature (ECT) sensor operation, replace if necessary.
* Verify proper intake air temperature (IAT) sensor operation, replace if necessary.
* If the above items check out good, replace the thermostat
* If Nissan vehicle, check for Technical Service Bulletins (TSBs), as the ECM may need to be reprogrammed to correct the P0128 code
Hope helps (remember to rate and comment this).
Remove thermostat and check to see if it has failed open. If it is open, replace thermostat. See my tip here to access/change thermostat http://www.fixya.com/cars/r5929960-s_thermostat
and let me know if you have questions.
SOURCE: Just changed my thermostat to a higher degree. Now
Let me get the problem straight. You replaced the thermostat with one not designed for you vehicle. And now you have a code. But you didn't have a code before. In my experience 99% of the time you need to look at the last work done which in this case was to install an improper thermostat. Yes it could most def be an air pocket. Or it could be the FI system is thrown off by the t-stat that takes longer to open. This is not like cars of old. The FI system expects to warm up in a fixed amount of time. I'd install the thermostat that the FI designers were expecting to be in your car.
SOURCE: coolant temp below thermostat regulating temp
more than likely the thermostat has stuck open. Or opening to soon not allowing the car to reach normal operating temperature. I would start by replacing the thermostat. Clearing the code and running a drive cycle and see if the code comes back. if the code does not return problem solved. if it does return replace the coolant temp sensor.
SOURCE: I have a 2003 Chevy Trailblazer that failed my
First, you should check to see if there is a thermostat in the engine or if it is stuck open.
SOURCE: Engine light came on with a code reading P0128
Most likelty the thermostat is stuck open, so replace it.
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