915is Low oil pressure troubleshooting

I did not mention that I suspect an inadvertent change in the Kanardia setup is causing a false oil pressure reading.

Temporarily install a mechanical gauge to confirm your suspicions.
If your EMS setup is incorrect;  ex. You have a 70psi sender and the EMS thinks it is a 150psi sender all reading will be halved.

I installed an OIL Pressure IDIOT Light in my initial build and got some flak over it.
It acts as a second opinion and I am glad I have it.

I am currently dealing with the same issue on a brand new 912iS. I have not flown yet and only have done ground runs. I performed the Rotax service letter for oil system purging and have been very careful to burp the system and check oil levels. After a few ground runs, I even inspected the internals of the oil tank, and changed/cut open the oil filter. At this point, I contacted Lockwood Aviation and there recommendation was two fold - 1) remove the oil pressure regulator cap, spring, and piston to inspect the piston for any fouling that may impact oil pressure regulation. 2) do exactly what you are proposing...plumb in a mechanical gauge to either verify the electrical indication coming from the engine to my Dynon EFIS or show that there is likely an issue with the engine pressure sensor.

I would be very interested in any other experiences people may have with this situation and what they did to address it

I disassembled  the oil pressure  regulator  and was surprised  to  find  the cover  was sol loose from the factory  with  no orings. After reassembly, all worked  fine. 

Same thing for me except mine is a 912iS. I removed the pressure regulator cap, spring, and piston. I cleaned it up and blew out some very small debris. I re-assembled it in accordance with the Heavy Maintenance manual, there are no o-rings required. Immediately upon firing upo the engine, my cold old pressure was back exactly in the green.