So it's stuck at low all the time? It's most likely your temp sender. Not sure on gen3's, but on a gen1, it's on the lower intake manifold. Behind the thermostat. Mine is out too. I hear you can only get it at a dealer.
I took out the thermostat a few days after I bought my car and I recently put it back so I dont know what could be plus the fuel needle stopped working too so i dont know whats going with this. My friend told me it could be the plug behing the instrument cluster but i dont know what could causing those things not to work.
Yes, the temp. needle stays low the whole time ... well in the gen.3 its in the lower portion of the thermostat ... the sender that you are talking about its something thats in orange next to the IAT i think right? and how much cost that at the dealer?