I just changed my thermostat housing, have it all back together, and there are no apparent leaks. The only reason I changed it was in hope that it would stop throwing a p0138 code, which it did three times, causing the cel to come on. I've started it a few times, and driven it a couple of miles. There is also a code p0117 now. I am wondering if it will clear the codes and shut off the light on its own, or should I clear them and start trying to complete the drive cycle again. I currently have two sensors showing incomplete...comprehensive and egr.
Fwiw, I never heard the cooling fan come on until after I changed the thermostat. Could the temperature have been THAT low?
one thing I just noticed...a radiator hose is very close or possibly touching the connector for the sensor. Maybe that interrupted the connection?
​Is it possible it threw a low voltage code (p0117) when it was disassembled and I turned the key on to put the car in neutral so I could roll it in and out of the garage?

 

It's actually showing 2 p0128 codes, not three....one p0117, and check engine light is on
( the two p0128 codes were there before the thermostat swap)

 

Codes self-clear if the fault has gone & remains gone, after 4 warm ups. (A couple of miles probably isn't a warm up.)

 

I had not checked for codes in over 10 years & purchased a new reader & got almost 20 codes on a car that runs perfectly; most of them were communication or electrical codes (C & U). I was wisely advised on this forum to clear the codes because, over time, there are some aberrations that, once the codes have cleared, won't show up again. So, I cleared the codes and only 3 appeared when I checked again. In my case, there has been no issue with drive cycle; perhaps it depends on the reader?

Having said that, I would listen to JagV8; he has always given me wise counsel.

 

Do you think the check engine light will also go off?

 

That is what he means!

 

It is, yes!

With no active codes the MIL will go off.