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-   -   P0128 Error Code (http://www.jeepgarage.org/f77/p0128-error-code-15646.html)

kyle.jg 11-29-2010 02:03 PM

P0128 Error Code
 
Hey guys,

My 5.7 HEMI gave me the error P0128 the other day as I stepped on the gas to pass someone. It was a cold day (about -20C) and I hadn't really warmed up the Jeep too much and the engine temperature gauge was just above the lowest marker. I drove with it for the day and then later that night I cleared the code using my DiabloSport Trinity. Since clearing it on Thursday night, I've driven at least 300 KM and it has not come back and it is now Monday afternoon.


Should I be taking this in to have it looked at, or don't worry about it unless it comes back again?

robpp 11-29-2010 02:36 PM

Re: P0128 Error Code
 
since it was sooo cold you might want to wait until it pops up again.

here is what the manual says about it:

Theory of Operation


The PCM predicts what the engine coolant temperature should be, based on the engine coolant temperature at start-up, ambient temperature and how the vehicle is subsequently driven. The predicted engine coolant temperature is compared to the Engine Coolant Temperature Sensor reading. The error between the two is calculated and integrated with respect to time. When the Thermostat diagnostic runs, the integrated error is compared to a calibrated threshold and pass/fail is determined. Separate pass and fail thresholds are used in order to improve accuracy of the diagnostic.

When Monitored:
Engine running.

Set Condition:
This diagnostic will fail when the model temperature reaches 91 C (196 F) before the ECT. reaches 80 C (176 F). This monitor only runs after a cold start condition ECT, ACT, AMB are all within 10 C (50 F) of one another. Two Trip Fault. Three good trips to turn off the MIL.


Possible Causes

LOW COOLANT LEVEL

THERMOSTAT OPERATION

SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

TEMPERATURE SENSOR

SIGNAL CIRCUIT OPEN

SENSOR GROUND CIRCUIT OPEN

SIGNAL CIRCUIT SHORTED TO GROUND

SIGNAL CIRCUIT SHORTED TO THE (K900), (G931) SENSOR GROUND CIRCUIT

OTHER POSSIBLE CAUSES

PCM

n8jay 12-10-2010 09:33 PM

Re: P0128 Error Code
 
I just got this error code as well, and same situation cold as all get out and probably 10 minutes into my drive. I am going to get a rad flush as I put in a bit of non HOAX coolant in. I spoke with the dealer and they suggest that a flush is in order, what do you guys think??? The coolant looks fine but their trying to put the fear in me, saying that the NON HOAX can cause corrision, metal and seal break down within the coolant system. Again I don't know. I haven't cleared the code or done anything, yet. I am getting plenty of heat inside the vehicle and the temp gauge sits just under half, is this normal? I'm not even sure were it sat before. Any help would be greatly appreciated.

Thanks
n8j

Scottina06 12-10-2010 09:43 PM

Re: P0128 Error Code
 
sounds like the tstat to me not opening/closing properly. get a new tsta when you have new coolant put in.

Siner)8 11-05-2012 04:16 PM

Re: P0128 Error Code
 
I'm also having the same problem. I've changed the tstat today and cleared the code but still getting code. also getting a p0004 for the trans

ALPINEST4RS 11-07-2012 09:49 PM

Re: P0128 Error Code
 
either a skewed ect or a tstat (as scott said)


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