Thermostat location and replacement?

It's on the side of the block. You have to remove the alternator to access it. Here is a guide to help you step by step with instructions in the diagrams below to show you how on your car. https://www.2carpros.com/articles/replace-thermostat Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

Check engine light code = P0128 was found indicating "low temp". I replaced the temperature sensor and thermostat (three different times) with aftermarket parts. Engine still will not come up to operating temperature of 192F. I am only getting a max temperature of 165F. Upon disassembling the original thermostat and comparing it to the aftermarket parts, I found that the original one seats on an o-ring and the aftermarket ones do not. Does that mean that the only thermostat that will work in this vehicle is an OEM part? Is that what I should try next or is there something else that could be causing my "low temp" error?

Hello, I am Danny.

Sounds like that is the case.. Those aftermarkets might be coming close but maybe there just running your car a little cooler. Putting in an OEM should take care of the problem. I have attached a tutorial for you but, I am sure you already know how to do it. Hope this helps and thanks for using 2CarPros.
Danny-

https://www.2carpros.com/articles/replace-thermostat