Not too sure where the temperature sender is on your engine without looking in the manual, Normally its situated near the top hose on the cylinder head. The best way to tell if its the gauge or the sender is to, when you've found the right connector. remove it and earth it out to the engine, turn the ignition on and the dial should shoot right up into the maximum zone and stay there, this would denote that the gauge is fine and the sender is knackered which is normally the case.