Got tune up now temp gauge messed up

GEORGIO123

MEMBER
2004 CHEVROLET IMPALA
6 CYL
AWD
AUTOMATIC
123,300 MILES

I got a tune up yesterday on my basic 2004 Chevrolet Impala and today my heat wasn't warming up so I took it back to the place and he put my car on the machine and said my thermostat needed to be replaced. As a customer I'm thinking they did something wrong because my heat was working just fine. But the mechanic said the temp gauge has nothing to do with a tune up. As I drove my car a little more the heat would get hot and then get warm. When I sit still the temp gauge in the car goes to the middle as normal but as I drive it goes a little below. Is this normal, should I give my tune up time to kick in? Did the mechanic possibly do something wrong? Or did the thermostat ironically go out the day after the tune up? Further, I got my inspection at the same place yesterday after the tune up and the thermostat issue did not show up on the machine.

2 Replies

DRCRANKNWRENCH

MECHANIC
3,380 POSTS

It is true that there are 2 sensors for coolant temperature. One is for the gauge and the other is used as a signal for the cars' computer.
The one for the gauge is usually near the thermostat housing and the other somewhere in the head or block.
The fact that it is going to the middle and then dropping shows that the thermostat is working correctly.
The thermostat reaches a certain temperature and opens up, then it drops the temperature of the vehicle. Sometimes when I work on my car I will, "over-analyze" related items like that.
So, it sounds like you are OK.
Keep any eye on it and if it changes, then you have an issue.

I hope this information helps.