has anyone else thrown a code for engine temp too low with a 180 t-stat? wondering if i need to let it relearn or if i got a temp sensor problem

 

It seems to be a issue for the 2001 models. Mine through a code so I just put the stock one back in.

 

A new temp sensor is about $9.00 at advanceauto. It may be worth a try. I was told the programming on the newer 2nd generation Rams was why it wouldn't accept the cooler tstat.

 

Congratulations! you get toreplace itagain!
I feel for you brother....read these:
https://dodgeforum.com/m_764121/tm.htm
https://dodgeforum.com/m_782330/tm.htm

 

I have a theory about this code, but I haven't been able to confirm it yet.

I used to hear people say this was because the desired warm-up operating temp of the engine is somewhere around 175. Once it reaches that, you have officially warmed up, and you go from open loop mode into closed loop mode. If you don't reach that temp, you get that code and you stay in open loop mode. So if you have a 180 t-stat that opens just a tad early, or your coolant sensor is not real accurate, you might make the PCM think you haven't reached 175 yet, and you will get the code (but you wouldn't have otherwise gotten it with a 195 t-stat).

I think there is more to it then this though becasue I started getting that code every once in awhile after I did my 180 t-stat install, but only when it was nice warm weather outside. On extremely cold winter days, my truck would often never reach operating temp due to the extreme cold. This happens whether or not I have a 180 t-stat or a 195 tstat. It is just so cold outside, the t-stat never opens because operating temps never get that high. I never received that code in this type of condition for as long as I have owned the truck. You would think you would see the code since I never reached operating temp, or even close to warm-up temp, but I never did see it. But on nice warm days, I would see the code, but only with the 180 tstat.

So what I think happens is that the PCM is also comparing ambient temps (as measured from the IAT sensor most likely) against the coolant temp measured by the coolant sensor before it determines if that code should be sent. I think that if the ambient temps are below a certain point, then the PCM expects the coolant temps to be lower, so it doesn't throw the code if you don't reach warmup operating temp (or maybe it has a lower operating warm-up temp when outside temp is below a certain point). But, if the ambient temps are above a certain point, I think the PCM expects that coolant temps to easily reach warmup temp, and maybe even exceed that temp to the point where the t-stat would open and coolant temps would stabilize (which would probably be set to 195-ish). So if the coolant never reaches 175 or 195, but ambient temps are high enough that the PCM would expect to normally see temps in that range, then I think it throws the code. But if ambient temps are not above a certain point, then it does not throw the code because the PCM knows that it might not be able to get up to normal warm-up operating temp. Just a theory.

 

makes sense, if the engine is in warm up mode it will burn richer, less mpg, and also after time burning the o2 sensor up then the cat. should have thought it over more before i put that stupid thing in.. thanks guys

 

just another example to consider.... i recently put in a 180* (with a hole drilled in it) in my 01 and it hasn't thrown a code. temp gauge comes up to about 1/3 of the gauge, within about 5-10 minutes, which looks to be about 175-180 and just sits there.

 

I put one in last summer. Made a big difference in how it ran - keep in mind I have several other mods. When the air temp started getting down into the 40's and 30's it threw the code. I blocked off about 1/2 the radiator with cardboard and was good for a while. When the temp got down to like 15 it threw the code again. I blocked off some more of the radiator and was good all winter. I changed out the t-stat in March just cuz I thought it might be the problem. I took out the cardboard shorly after that. It got down into the low 20's for like a week in the middle of April, and I got no code even with the cardboard off. Based on that information - I have to assume that the first 180 stat I put in was opening a little early and not allowing the computer to switch to "normal" mode.......

 

What brand of thermostat were you using?

 

this is why its a good idea to test them in a pot of water before the install. only takes a few minutes and imo a t-stat can be a less than perfect device. in the old days, it didn't much matter if it opened a little early, as it just delayed your heater a little. the risk used to be that it would open slow, or not at all. now with the pcm monitoring everything, you have to worry about it both ways.