01 Passat Engine Light and Temp Gauge

My 2001 1.8t has 43k on it and has been trouble free. Until now.

The engine light came on with no info provided. I drove it for over 20 minutes when the temp gauge dropped to zero then back to 190. After a few more miles the gauge jumped up and down several more times. I returned home with the gauge at zero. I turned the car on after 15 minutes to find the temp gauge back to 190 or so and the engine light still on.
Here is the kick: Around 1 hour later or more the panic alarm started to go off and then stop. I reset the alarm with the key FOB and waited. Nothing has happened since.

I am looking for a reputable mech. here in Seattle to give me a diagnosis. I hope to have at least one more opinion after that.

Code Scanners: Is it possible to have someone read the codes and make a educated guess? Will the code lead in the proper direction or should I expect to have pumps and sensors changed before my temp gauge is finally replaced? And is it possible for me to replace the sensor myself and will the code reset and drop the light?

Any experience or suggestions are very much appreciated.

i had a similar problem with my 92 passat. temp gauge, a/c, cruise, fans sometimes worked, sometimes were dead. especially the alternator wouldn't charge the battery.
the techs traced it down to loose contacts behind the instrument cluster.
hope it helps. cheers,
luke