Modern Vespa

The fan on my GTV keeps coming on. I've checked the water and its ok, it's like when a car is stuck in traffic and starts to overheat.

Is it actually overheating? Is the water properly circulating through the system ie no leaks? The hose clips are poor quality- best to change them anyway. The temperature sensor could be at fault. Same thing happened to me and it was my water pump not pumping but all the above was checked first.

Where are you? In the summer, in stop and go traffic mine comes on too, (I have a 2009 GTVie). I think that is normal. Unless there are indicators that oh are overheating I don't think you need to worry. I think your fan is doing its job. When I first got mine I sort of panicked too. But unless there is something else going on I think you are fine.

Have you by chance checked coolant levels..?

Coolant and water is fine.

No leaks, levels don't change.

Cheeky thinks a poor connection to the sensor.

Not sure how I can tell if the water pump is pumping?

I've had it come on in hot weather after a bit of a ride but the temp is high at the moment and it starts almost as soon as I start riding.

I was going to suggest seeing if you could pick up any small vibration from the outer cover of the pump, that'd indicate if the 'propeller' vane was spinning, but having looked at the exploded diagram, I'm not sure you'd feel it...

I've replaced the Thermostat (item three), bled the system, removed and cleaned the water sensor (twice, once with a cloth and once with wire wool), i'm now going to replace the water sensor (item eight).

disconnet ECU for 1 night, It improved the situation in my case

Disconnected the battery for about a week, reconnected today and ran her at idle for about 10 minutes. Took her for a brief run and voila no fan kicking in. After the Ace meet and the lumpy ride, poor starting etc. she seems like new again. 8)