It's actually just a dumb level switch. Normally open for normal level of oil, then when the level drops to a "low" level, the float makes contact with another contact which is earthed.
So if there's a short in the wiring, and there's some earth leakage, that could be the reason for the CEL.
Or perhaps the float is stuck in the down/low position?
If you have a DVM, check between that single contact and the body of the sensor to see what resistance it shows, then clean the thing up real well and see if you can find any scrapes in the insulation, or problems with the float. Carb cleaner works wonders on these.
If the above doesn't work, contact "Aliga" who's a member on here. He's always parting out Lexus cars & motors, and probably has one of these for not much $$. Several of us have bought from him, and he's fair on prices, and has fast delivery.