Thermostat going up and down

We have a 2003 Malibu v6. My wife pulled over and called because the overheating light came on and the temp gauge was pegged all the way. She started the car a few min later and everything was fine again. I drove it just the other day and watched the temperature go from no temperature (gauge all the way to the bottom) to hot (all the way to overheating) in under a minute. I kept driving and the temp went to normal then back to hot again all within about 2 minutes. Is this a cooling issue or a thermostat issue? My father in law says replace the thermostat and it'll be good. Any ideas?

Possible air in the system due to a very low coolant level.

As stated above, check your coolant level. You may have a coolant leak. Were the cooling fans running? You say the gauge was pegged hot? It's also possible you have a bad temp sensor. Yes, a thermostat is also possible.

I agree.

We have a 2003 Malibu v6. My wife pulled over and called because the overheating light came on and the temp gauge was pegged all the way. She started the car a few min later and everything was fine again. I drove it just the other day and watched the temperature go from no temperature (gauge all the way to the bottom) to hot (all the way to overheating) in under a minute. I kept driving and the temp went to normal then back to hot again all within about 2 minutes. Is this a cooling issue or a thermostat issue? My father in law says replace the thermostat and it'll be good. Any ideas?

since this is always failing look for this . when in the overtemp range is the engine really overheated ? are the fans running ?

coolant should be a pink color . if its dark brown you may have sludge in the coolant from mixing dexcool with non gm approved dexcool spec.

when this occurs blockages cause this type of issue ....

Like the guys said, check the level first....

Had coolant flushed and filled. The temp gauge acted normal for a while.

Had coolant flushed and filled. The temp gauge acted normal for a while.


did you have the sludge in the coolant/engine ? if so keep close watch on the coolant to get sludged up again. only use distilled water and dexcool ..try to keep it at 60 % dexcool to 40 % distilled water. you can go up to 70% dexcool for max protection .