Check Engine Light-P0128 Thermostat

I just had my check engine light come on my 2017 Tacoma. Reader showed a code for P0128 stating the thermostat is potentially stuck open. When driving my engine temp needle doesn't really move showing it's heated up but vehicle runs fine. Everything I researched showed that I needed to replace the thermostat, questions is if anyone has had experience with this and if its better to replace just the thermostat or the whole unit. Also, done normal vehicle maintenance like oil changes, spark plugs, engine coils so not sure if this project is too much for me to handle. Looking for advise on the code mostly and if anyone has had experience!

 

Welcome to TW!

 

It’s a complete unit, very common.

 

ECT sensor check! Before replacement of thermostat.

 

Thank you both very much! I'll look into how to do an ECT sensor check first and then will probably just do a whole unit swap if that's all good!