Rev counter a bit iffy

hiya all, this problem has just started, on tick over the rev counter is not registering but when riding it moves but not showing correct engine speed to road speed (i.e. 40 mph =1500 rpm ish in 4th gear) then when stopped at a junction it registers 0. I've switched ignition off then back on and it works as it should. its baffling me. Bike is a 2010 F 650 gs 800 miles on the clock anyone else come across this problem?
cheers Alan

sounds like the sensor rather than the instrument itself maybe?

I had this when the potentiometer (gear indicator) went. In addition wouldn't show neutral or would show it at the wrong time.

Just so you're aware if you unplug it for inspection / refitting the whole bike will need to go back to dealer for recalibration.

Best,

S

thanks for the replies lads, i'll keep an eye on it and see if anything gets any worse. i washed the bike yesterday and it worked as it should