Hi Mad mark,
First, 13 and newer USDM FB20 engines all had oil level sensors in the upper oil pan. This engine was actually first used sometime around 2010 in JDM applications. So I think it's more likely your JDM engine is older, not newer than your car.
That said, my assumption is that you've already installed the engine into the car when you noticed this difference.
If not, I would suggest you swap the upper oil pan from your old motor onto the JDM motor. These engines are notorious for oil leaks anywhere there is sealant used.....which is in A LOT of places on these engines.
To be more specific, Cam carriers, timing cover, upper and lower oil pans are all known to leak through the sealant on these motors anywhere from 30-60k miles.
When I do these swaps I always reseal all of the above mentioned components on the JDM motor before installing it in the car.
If you've already installed the motor and aren't wanting to take it back out to swap the pans the only real options I see would be to rig the sensor to stay in the full position, plug in the sensor, and zip tie it up to the block somewhere. This is a pretty hokey work around but it should work.
I personally have never attempted to trick the ECM for this issue.
However, looking at the wiring diagram for that sensor, it looks like the sensor is a normally open circuit which closes when the oil level is full. In theory, that would mean one could ground that sensor wire to the block which would trick the ECM into thinking the oil is full all the time.
Again, I personally have not tried that and if you have not already installed that engine into the car I would recommend just swapping the upper oil pan from your old motor.
Let me know.
