To my knowledge they are not reset-able, more likely you have a short somewhere.
The unit is connected to a brass tube that sits verticaly in the oil tank.
In the tube is a long thin PCB with several reed switches that are activated by a magnet attached to the float as it moves up and down.
You could try moving the float up and down the sender to see if it resets.
The sender unit is very expensive to replace @£100, but Suzuki recommend them as a service item every 2 or 3 years.
I had a similar problem with the one I had a few years ago on a DT40. The gauge was fine but the sender unit was corroded badly inside when I cut it open.
I removed the whole thing in the end and remembered to keep an eye on the oil level.
If you decide to do this beware, as the unit will fail safe, set of the alarm and cut the revs to get you home mode.
I made up a patch cable to replicate the top reed switch being activated and never had another problem. Did keep an eye on the oil level though.
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