Jaap Nauta wrote:
> Probably bad sensor or contacts. If the needle stays in the middle, temp
> is fine, and the red light indicates level too low. Level was OK, so
> sensor is bad I guess.

Don't overlook that, when there is air in the system, revving up the
engine will cause the coolant in the expansion tank to go down and can
cause the red light to flash.  Then, when you shut off the engine and go
back to have a look, the level comes back up so it "Looks" OK.

Mike