False overheating warning on twin 1999 200 saltwater series outboards

[kelld8616]

I've been having issues with my twin 200 outboards. I'm getting a false overheating alarm and the engines go into limp mode/cut out. I've had a Yamaha tech check the thermostats and impellers and they say everything is normal. I also had them compression tested and heat tested and everything there is fine. I recently had the tachs replaced and noticed that even though the two throttles are at the same place on the remote, the engines run at different rpm, sometimes as much as 1000 rpm apart. This issue doesn't happen at WOT however and the motors are happy to run at WOT all day long. Is it possible that the lack of synchronization from the remote is causing a false (or real) warning and cutting the power?

Thanks for your time,

D

[rodbolt17]

throttles wont affect the warning system.
does the tach actually indicate an overheat?
the alarm tone is the same for ALL alarms.