CEL went on the other day. It came up as a P0128 Code (basically bad thermostat from what I read). I cleared the code and it hasn't come back since. I've been monitoring the coolant temperature on my DIC and it's reading normal. Should I bother changing the thermostat if the P0128 code doesn't come back? Car has a little over 90k on it.

 

have you replaced the thermostat before? i'm a preventative maintenance guy so i would say change it cuz it's cheap and easy fix but as long as your temps are staying solid where they're supposed to, it might've been a single bad read that caused the code

 

No. Other than oil/filter changes the only maintenance I've had to do so far is replace the fuel pump.