[Engine] Overheat and antipollution?

[cancunia]

At least the code is consistent with your temp readings. Maybe disconnect the sensor and see what the gauge reads when you have the engine warm. Is the gauge at zero when the engine is cold?
I'm totally guessing here, but if the sensor decreases resistance as it gets warmer (?), maybe you can do a controlled short to ground with an extra piece of wire and see if the gauge moves. A multimeter would be helpful to check my guess. Lexia may be able to tell you the coolant temp, Torque via an OBD adapter certainly will.