My scoot showed 4 bars when I got off the highway as in overheat.
History:
Currently at 21,500 miles. Only time other time I had an issue was when I changed the antifreeze at around 12K mi and did not get all the air out of the system. Today in ~ 87 degree temps on the highway i noticed 3 / 5 bars lit - usually runs at 2 bars unless it is really hot out. On the way home I noticed 4/5 bars and briefly 5 blinking bars / boxes. Checked coolant and it was not low, also coolant in the reservoir was only lukewarm.
UPDATE: I removed the thermostat and it took a while to warm up but the display showed overheating. I rocked the scoot side to side to expel air with radiator cap off. The radiator was not very hot.
UPDATE: Yesterday the scoot ran fine and today too. Today temps were as high as 87 and I did a mix of highway and sitting in traffic. No problems. Also, yesterday I was at 2 bars (normal) and on a side street the gauge jumped to three then bars then back to 3... and two again. I'm wondering if it is a loose wire or something?
Final Solution: replaced the head gasket then no more overheating issues. I reinstalled the thermostat a few months later. No problems even on the highway at full throttle in 85+ degree weather.