Need a suggestion DTC Codes P0128 & P0453

I have a 2002 Grand Prix 3.1. The service engine soon light has gone on and off a few different times. I took it to Autozone and the codes that came up were P0128 (Coolant Temp Below Thermostat Regulating Temperature), so I am assuming that would probably require the Thermostat to be replaced. The other code was P0453 (Evaporative Emission Control System Pressure Sensor High), I have no clue what that possibly could be, so any help any of you have would be great. Also, while I've got you here, I live in Seattle and it has been really rainy, as usual, but I noticed that my driver's side floor is soaked, the passenger side is completely dry...does anyone have any ideas or suggestions?? Thank you.

Welcome to AF!

P0128 ECT Below Thermostat Regulating Temperature
P0453 Evaporative Emission Control System Pressure Sensor High Input

They got the code definitions correct for once, :lol:

The P0128 is almost always a bad t-stat (stuck open). Occasionally, it is caused by a bad CTS (coolant temp sensor), but not often.

The P0453 is most likely a blocked/pinched vent hose or bad tank vent valve.

Thank you for your help. Its nice to be able to go to a mechanic with a general idea of what is wrong with my vehicle...Have a great weekend :)