Error code P0128

Question edited for clarity. The code is capital P and zero, not small p and oh (o). Plus toss in some caps and move to model category.

Error code P0128 indicates that your engine coolant temperature is below the thermostat regulating temperature. This means that your Engine Control Module (ECM) or Powertrain Control Module (PCM) has recognized that your engine is running cooler than it's supposed to.

P0128 Code ' KBB - Kelley Blue Book

Question edited for clarity and add a few spaces and capital letters. :>D
Question moved to model category.

That code is the opposite, it isn't REACHNG temperature it should. However, I had that code and changing the thermostat, got rid of the code.

Error code P0128 indicates that your engine coolant temperature is below the thermostat regulating temperature. This means that your Engine Control Module (ECM) or Powertrain Control Module (PCM) has recognized that your engine is running cooler than it's supposed to.

p0128 Code ' KBB - Kelley Blue Book

Videos in the link Julie.

https://www.google.com/search?q=Toyota+Highlander+Hybrid+Limited.+How+to+replace+thermostat

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P0171 is a lean code indicating more air than fuel being burned in the engine. P0128 is refering to the coolant temperature being below operating temperature. Usually this is caused by a defective thermostat. There are many reasons for a lean code to develop. This code may be due to the thermostat not operating correctly. Have the thermostat replaced and clear the codes to see if P0171 returns. If it does, further diagnostics will be required

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

Read more at: http://www.obd-codes.com/p0128
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First code P0771 is shift solenoid E is stuck or has a performance problem.Code P0128 could be low coolant,leaking or stuck open thermostat,faulty coolant fan (running to much) or faulty coolant temperature sensor.Code P0171 fuel system to lean usally its a dirty mas air flow sensor or a weak fuel pump,fuel filter or fuel pressure regulator. Code P2195 is oxygen sensor stuck lean bank1 sensor 1.I would check for low fuel pressure causing the lean condition or faulty injectors (clogged).Also i would replace the coolant temperature sensor.

P0101 is the Mass Air Flow Sensor error,
http://www.obd-codes.com/p0101


P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature

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 this answer).

Unless the car is overheating you probably just have a bad temperature sensor probably located on the intake manifold....

PO172 means that an oxygen sensor in bank 1 detected a rich condition (too little oxygen in the exhaust). I would replace the thermostat first. The computer could be injecting too much fuel because it thinks it never gets to operating temperature. That may keep the light off.