This has been an on going issue for me for the past year, it would come for a 3-5 days and go away for a few months. Sorry for the vid quality , i recorded this going to work this morning with my cell windows down lol, just pay attention to the coolant gauge and you will see what im talking about. sometimes the gauge will dip down to he first line above the C mark causing my idle to raise and my car to run too rich with a noticeable decrease in performace when accelerating half or full throttle . It has thrown the thermostat code before (P0128) if i remember correctly, which would also clear itself after a few days of the coolant gauge performing like it should. I wanted to see if any of you have seen this before, I do have a new thermostat ready to install but wanted to see what you guys think and if it could also be a coolant temp sensor.
Thanks in advance for any help
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Could def be a temp sensor, i'd say check that first, easier and cheaper to replace than the t-stat.

 

i bought a thermostat a month ago when i did a bunch of maintenence on my car just didnt feel like installing it after all the other things i did that day, cost $24 at infiniti but nissan dealerships here were selling it for $37 , wtf! . thanks ill look into the temp sensor or sensors in case we have two. just drove it a bit for lunch and it was fine lol

 

If your thermostat was bad, you would have been overheating already or close to it. I would check the temp sensor. Try to find the diagnostic procedure on the coolant temp sensor, check with a ohmmeter and find out if it's bad. Sometimes they don't give off a check engine light.