P0128 Code Problem

trat73

New member
[FONT=&quot]Hello all. [/FONT]
[FONT=&quot]Having an issue on 2006 2.4L TJ. The P0128 code keeps coming up. I've done the following:[/FONT]
[FONT=&quot]Replaced thermostat with Stant 195 SuperStat[/FONT]
[FONT=&quot]Replaced the Coolant Temperature Sensor (also Stant)[/FONT]
[FONT=&quot]Flushed and Burped the coolant. [/FONT]
[FONT=&quot]Still getting the P0128 code. Any ideas?[/FONT]
 

P0128 code happens when the PCM doesn't see the temp hit 65 deg within a certain time from start.

Where do you live? Winter here can cause this or a Thermo stuck open or opens early.


First clear the code by disconnecting the battery and turning the key to on then off and reconnect battery. See if the code returns.
When you changed the Thermo was there anything wrong with the old.?


Did you put Teflon tape or anything on the new temp sensor?

Here was my issue....Thermo early failure.
https://www.jeepz.com/forum/cj-yj-tj-jk/37116-p0128-thermo-failure.html


Regards,
JPNinPA

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Last edited:
Hello. Thank you for getting back to me so fast. I had recently purchased the Jeep when the code first appeared. I have a reader and cleared it after I replaced the thermostat with the Stant Superstat 195 and flushed the coolant. It came on again and I changed the sensor (it had a coating on the threads so I didn’t Teflon). It is now on a third time so I ordered the standard Stant thermo and will try that. Did your prob go away after installing the Napa thermostat?
Thanks again!!!


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Yes
Some of the thermos like super stat are built to fail open. And that is just what they do. If you followed my link you could see the few month old thermo that failed. My guess it failed within 2 weeks. Cause gas milage came and went.
Sad but true there are aftermarket parts that fail out of the box or within a month.
If you need any sensors, buy OEM.

PS Stant makes the OEM part #14209 The bleed valve should be positioned at the top when installed.


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Last edited:
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