P0501 Volkswagen -

Question

I have a 1997 Jetta and I checked for codes and P0501 came up. My my instrument panel/cluster does not work very well. Temp. not true (always pegged hot), speed odometer doesn't work most of the time, and I don't trust the gas gauge. That said, this is the first time for this code. One of the symptoms is speed odometer may not work, so is there something else I should check and where to look?