问:温度传感器

有2006雪佛兰蒙特卡罗ls。开车不仅但两英里和温度计下降一直到冷。仪表盘说发动机热交流。拉过去。引擎并不热。绝对没有过热。带回到经销商(是测试驱动),他插进小诊断电脑的事情。恒温器。他取代了它。与此同时我google了一下却看到这种情况很多。在GMs,人们有很多不同的答案。 Well he fixed thermostat and it was fine. Bought car and drove for 2-3 days and it did same thing. He said he would try to figure out what's wrong but I'm hoping we can find real answer real quick. Didn't buy a car to keep having it taken away to figure it out. Have alot of important appointments this week where I have to travel 3 hours away for one and need quick fix

我的车有120000英里。
我的车有一个自动变速器。