2016 Challenger Hellcat, I'm getting a P0128: Coolant Thermostat – Below Temp. I've had a 180 deg thermostat in it for 2+ years, through 3 winters at least. This just started happening. I read that this almost always the thermostat. I've had to put in several 180 deg stats over the years, cause they start going whacky....185 to 225, like its sticking closed (I'm aware it needs a tune to truly work with a 180) No tune will only cause it to get to bout 200 at a red lite, Afterwards it gets wind. I also read that it could be be the wiring/sensor associated with engine water temp detection, or the coolant temperature sensor itself. Says if the P0128 comes up but the engine is at temp, that could be the sensor. My question is - where is the coolant temperature sensor?
Found this on another site; Coolant temp sensor should be in the water pump's body, as pictured below (#4).
Ah where did you get this? does it have a part name or #? I wonder if this is a do it yourself. If cheap and easy enough, I;ll change it ....jus becuase. My next goto move, is I have an OEM thremostat from Dodge.....195 deg. Put back in what it came with.
that was my plan, but want a part name, to make it easier......I'm guessing its called a "coolant temperature sensor", if not that should get me close.
I swear back in 2017 when I first put in a 180 deg the OEM was a 203 def stat? But the OEM I just got is 195. I've had in 2 gates and 2 other hi end stats. Same thing every time. They work fine for 6 months, then, they start acting flakey ....going up to 225, even when doing 80mph.
Google is your best friend Here is a link to 2015-16 service manual and some screen shots from my 2017 manual. Page 7685 has the code trouble shooting procedures. https://www.dropbox.com/s/s384g1sauodvjx3/Dodge Challenger 2015-2016.pdf?dl=0
NICE, thanks. I had read all this , but not in a manual...someone had written it up, saying 96% of the time its the thermostat, but could be the sensor. and he listed out these steps ...basically if the engine reached operating temp, within 2-5 minutes I should NOT get a P0128 if so....could be the sensor/ i downloaded this manual but it only has 5539 pages. Where/how do I get to page 7685 code trouble procedures?
No doubt in my mind the 'stat is your problem. Not sure why you'd have repeated failures. I'd want to examine the failed part. Regarding using a lower temp 'stat, it generally offers no benefits on even a relatively stock engine and can cause several problems, especially in modern computerized applications. I know it's one of those parts that large amounts of diy hot-rodders love to change but there's simply no reason to in most applications.
it had a 203 in it....the 180 works fine except where no air flow whether it be a stop lite, no fan on. Without a tune the Fan only know to come on at 203. So if its moving it hovered at 180 and fan comes on less. I've had two gates and 2 of the other hi end stats in it. After a few months they all, ........must be sticking closed, even while moving temps toto 222. it would flake like that a day or two then go back to normal. With a 180 , and no tune....it goes on up to what the PCM last knows as "the stat is programmed for"...min was 203. so at long lites up to 203 it goes and then fan comes on or Im at 80mph...back to 180. This my fourth car i've added the 180 no others had issues. This P0128 is not the same as the flake out issue. It says car stayed below operation temps too long. I read where its always the stat,,,BUT, if its giving a P0128 and car is at operation temp...could be the sensor. The 3rd possible cause is simply "the PCM".
