You'll need to download the wiring schematic and the service manual(links are on FB group or here as well I believe).
If I had to guess I would say either the sensor(likely) or the wiring(possible) are causing your error code/issue. Locate the sensor and follow the wiring making sure connections are tight etc. Visual check. Then disconnect connectors where you can and make sure not corroded. While opened up, never hurts to add some dielectric grease on said connections.
Thinking service manual would have a test for the sensor. You'd need a multimeter and then compare readings against what manual says is in range. Looks like a $60 part if it is that. #18 on this diagram. I've had that part fail on a VW Passat but that was a known problem for them. Doesn't look like a terrible job IMO... That assumes the sensor removal won't cause coolant leakage. If a lot there then you'd have to fill which is a small PITA. If just a tiny amount you could top up through the resouvier which is still a gymnastics event but better than partially removing the tank!!
2012 Yamaha STRYKER (XVS13CBO) Electrical 1 | Rich's Yamaha
Could also just be wiring that got kicked loose or something simple like that. Check that as well.
Doubtful either the thermostat is stuck or water pump is bad since if either of those you would have overheated or bike would have shut down preemptively.
