Question about 2004 Jeep Grand Cherokee

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Check engine light code on for engine coolant

Check engine light code on for engine coolant temperature sensor replaced sensor and thermostat reset computer same code came back and temperature gauge fluctuating hot to cold

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Check continuity of the sensor wire. It should run between pin #4 (check manual (chilton better than haynes for electrical) for location as sometimes there are design changes) of the black harness plug on the computer to the sensor. The other sensor wire is shared with the cps and tps sensors, so if you don't see problem readings with those that wire is likely good.
Also, make sure that you have no air in the cooling system or as it passes the sensor it can mess with the readings. Run the engine with the system open and the heat on high....I like doing this with the front of the vehicle either jacked up slightly or pointing up-hill... run a complete "cycle" from cold to operating temp and add coolant as needed.
Hope this helps!

Posted on May 12, 2010

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I have a 2006 Buick Lucerne V6 code po128 comes up. What does it mean?


P0128 BUICK P0128 BUICK - Engine Coolant Temperature Below Thermostat Regulating Temperature Repair Importance Level: 3/3 Repair Difficulty Level: 2/3 help.jpg Share facebook.png twitter.png linkedin.png google-plus.png sep.png print.png pdf.png share.jpg 3 comments.png ' Add Comment xicon.jpg http://www.autocodes.com/p0128_buick.html Forum Code Possible causes - Leaking or stuck open thermostat
- Low engine coolant level
- Insufficient warm up time
- Faulty engine coolant temperature sensor
- Engine coolant temperature sensor harness is open or shorted
- Engine coolant temperature sensor circuit poor electrical connection
help.jpg What does this mean? Tech notes If cooling system is not leaking and the fluid level is OK, replacing the thermostat usually takes care of the problem.
help.jpg What does this mean? When is the code detected? If the Powertrain Control Module (PCM) detects the calibrated amount of air flow and engine run time have been met, and the Engine Coolant Temperature (ECT) has not met the minimum thermostat regulating temperature, the code P0128 will set. Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light) P0128 Buick Description An Engine Coolant Temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the Powertrain Control Module (PCM) for engine control and as an enabling criteria for some diagnosis. The air flow coming into the engine is accumulated and used to determine if the vehicle has been driven within the conditions that would allow the engine coolant to heat up normally to the thermostat regulating temperature. If the coolant temperature does not increase normally or does not reach the regulating temperature of the thermostat, the diagnostic that use ECT as enabling criteria may not run when expected.



Read more: http://www.autocodes.com/p0128_buick.html#ixzz3vprh5jzz

Regarding which thermostat to use, I am guessing it depends on where you live.

Ask these people when you order the thermostat.

http://www.autopartswarehouse.com/shop_years/buick-lucerne-thermostat-2006.html

Dec 30, 2015 | 2006 Buick Lucerne

1 Answer

I have 2008 PT Cruiser; getting P0128 code; I've changed thermostat & temperature sensor; I have to fill the anti-freeze container every 2 weeks; temperature hand will not always be at half way point. ...


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. 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.
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
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
you have all ready replaced the thermostat with the proper temperature opening thermostat(hopefully) and coolant sensor, you say you have to refill the coolant every 2 weeks this indicates that you either have a coolant leak that needs to be checked out and repaired or you are burning coolant which indicates a possible head gasket problem which will have to be checked. a low coolant level will set this code as there is not enough coolant in the engine to get the engine to operating temperature and stay there. these last suggestions is where I would start to look.

Sep 24, 2014 | 2008 Chrysler Pt Cruiser

1 Answer

2004 trailblazer code po128


P0128:
P0128 OBD-II Trouble Code
Technical DescriptionCoolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

What does that mean?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.

CausesA 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 .Here's a link on replacing your thermostat.

Feb 06, 2013 | 2004 Chevrolet TrailBlazer

1 Answer

P0128 code on 2006 ford escape, solutions?


Diagnostic Test Code (DTC) P0128 has a generic description of "Coolant Temperature Below Thermostat Regulating Temperature".

The Poertrain Control Module (PCM) checks the coolant temperature at startup. It then calculates the period of time that it should take for the engine to reach operating temperature (or thermostat regulated temperature). After the calculated period of time, the PCM again checks the coolant temperature. If it has not reached operating temperature, a code P0128 flag is set in mode 6.

If the engine still has not reached operating temperature after 5 more minutes of continuous engine operation, code P0128 is set in continuous memory and the Check Engine (or Malfunction Indicator Light "MIL" is turned on.

Possible causes:

> A stuck-open engine coolant thermostat (MOST common)
> A skewed Engine Coolant Temperature (ECT) or Cylinder Head Temperature(CHT) sensor (working, but not reading correct temperature)
> Low engine coolant level (causing the sensor to not read correctly)

First, the engine coolant (antifreeze) level should be checked. If it is low, it is recommended to perform a cooling system pressure test to find out WHY.

Then, the actual engine temperature should be measured with an infrared thermometer near the ECT or CHT. The reading from the thermometer should be checked against the live sensor data with a scan tool. (PLease note that MOST generic OBD code readers CANNOT perform this function.)

If the reading from the thermometer and the sensor data is within 10 degrees F of each other, replace the thermostat. Otherwise, the sensor circuit should be checked for high resistance (loose or corroded connector, damagd wire, etc.). If no high resistance is measured in the rest of the circuit, the sensor should be replaced.

Jan 03, 2012 | Ford Escape Cars & Trucks

2 Answers

Eror code: PO128 Code


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
Other ECT sensor and circuit related DTCs: P0115, P0116, P0117, P0118, P0119, P0125

Feb 08, 2011 | Buick Rendezvous Cars & Trucks

1 Answer

I have a 2004 Chevy Impala. As I was driving home yesterday I had the heater on full blast - temp outside appx. 60. The check engine light came on and I had a P0128 code. Could this be due to keeping...


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.


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

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


REFERENCE: http://www.obd-codes.com/p0128


I hope this helps a bit!

Jan 11, 2011 | 2002 Chevrolet Venture Passanger

1 Answer

Error code po128


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).

Jan 07, 2011 | 2002 Chevrolet Venture Passanger

2 Answers

P0128 coolant temp below thermostat/regulating temp


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).

Sep 27, 2010 | 2006 Dodge Caravan

3 Answers

What can keep causing Check engine code P0128


CODE P0128- THERMOSTAT MALFUNCTION. POSSIBLE CAUSES 1. ECT SENSOR IS OUT OF CALIBRATION. 2. CHECK THE OPERATION OF THE THERMOSTAT IT MAY BE STUCK OPEN.3.INSPECT FOR LOW COOLANT LEVEL OR FOR AN INCORRECT COOLANT MIXTURE.

Jan 06, 2010 | 2004 Kia Spectra

3 Answers

I have a code P0128, what is my problem is this in the cooling system?


This code is for your Coolant Thermostat - It's detected that the Coolant Temperature is below the Thermostat Regulating Temperature

This code may mean one or more of the following has occurred:
  • Low engine coolant level
  • Leaking or stuck open thermostat
  • Cooling fan running too much
  • Faulty coolant temperature sensor (ECT)
  • Faulty intake air temperature sensor (IAT)
Check the following to see if it resolves your problem:
  • verify coolant strength and level
  • verify cooling fan operation and replace if necessary
  • verify ECT sensor operation and replace if necessary
  • verify IAT sensor operation and replace if necessary
  • if all above checks out, replace the thermostat

Oct 16, 2009 | 2002 Buick Rendezvous

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