[270+camry]

ok, u might think im crazy, but if it ever does it again, tap the gauge cluster hard, like a love tap. if that sends the gauge all the way back to cool that could mean that you have a loose gauge conection. you can do that or pull ur gauges and check to see if the temp gauge is all hooked up right.

also doesn't hurt to test your gauge and temperature sending unit. if your temp sendin unit is faulty it can make your gauge act like it is off it's meds.

the reason why i suggested to sucker punch (lightly) your dash method is because my car does that. it reads cool and sometimes for no reason shoots to way past hot, sometimes it stay there and sometimes it drops back down to cool just as randomly as it shot up. sometimes it would even read as hot as soon as started my car after it was parked all night. freaked me out once or twice untill i got mad and punched the gauge cluster, which sent my gauge to cool. next time it shot up randomly i gave the top of the instrument cluster a light (in my standards) tap and it reset the gauge, in my opinion, the connection is loose which is giving it a false reading.