Replaced the coolant temp sensor and thermostat. It was done 2x with new parts due to leak on first install which is now gone. Reason for change was check engine light and code p0128c. Code is able to be read and cleared but comes back. Sometimes it takes 20min and 1 trip. sometimes hours and few startups and shut downs.

Read that a battery can throw a false p0128 but battery sits at 12.5 to 12.6 not running. I did notice that when the code came on last time, I saw the temp gauge fluctuate as I was trying to monitor it. Car starts runs and drives fine.

Not sure if the outside air temp sensor is related but air temp reading is off by 10 degrees high or so but has been that way as long as I remember(not sure how to get to it and if it can be cleaned, relocated or recalibrated.)