Im new to this forum, so if im in the wrong area, please let me know.
I bought a 2005 mazda 3 two days ago. Used and has quite a few miles on it.
As I was driving today, the check engine light came on. I stopped at advanced auto and had them read it, and it said something about the temperature was insufficient to remain stabalized or something. Cant remember his exact words. Anyways, they told me to put antifreeze in it, or possibly change the thermostat if the antifreeze didnt work. Then I found out the car had nearly no oil in it. So we put oil and antifreeze in it. Check engine light is still on.
Was just wondering if anyone else had this problem and may be able to suggest what it could be? I was told if it was my thermostat, that it would run hot. And its running almost cold. Sometimes its right in the middle but stays mostly toward cold.

 

Get a copy of the code check.

 

The thermostats on the early 3's tended to go bad and get stuck. Depending on what position it gets stuck in changes whether it runs hot or cold. I'm pretty sure these tend to get stuck in the open position which means it would run cold (read: can't keep the coolant in place long enough for it to get hot).

It's a relatively straight forward replacement if you have a few basic tools and some time on your hands. IIRC the Mazda thermostat runs around $40-50 but don't quote me on that. Given reviews online DO NOT buy a generic thermostat at an auto parts store, get the Mazda one. They released an updated and less prone to failure one, and the generics are terrible quality.

Basically you:
-jack up the front of the car
-drain the coolant
-take tension off the main belt
-remove the tensioner pulley assembly (three bolts)
-remove the hoses from the thermostat (possibly a few bolts?)
-replace and reverse order and refill with antifreeze.

 

^^ Also get it rescanned and see what the code/message is.

 

Awesome. Thank you.