Jeanie wrote: I have no Idea how to find or test the sender.
sender is located on the thermostat, simply remove the wires to it and join them together with the ignition on, the gauge will then go to maximum, if it does then the sender is broke.
flashing light indicates low water in the expansion tank.
the gauge is very delicate... be careful if you "fiddle" with it
AGG 2.0L 8V. (Golf GTi MkIII)