After powering up the aircraft for pre-flight checks, there was a obvious problem on the engine page.
ECAM oil pressure (and quantity) is derived from the analog oil pressure/qty indicator. In this case the needle is down at zero and the only way to rule out the transmitter is to run the engine. Instead of an engine heat cycle some simple things can be tried first.
Believing that it could be a "downstream" problem. Simply selecting each SGU off will put both ECAM screens on a single unit.
The problem remained on either SGU. Moving "upstream", a cycle of the SDAC breakers was tried.
The problem remained after the breakers were reset. This did not rule out the SDAC, but the damn things come up stupid at times.
The only thing left to try before being forced to either open up or start the engine is a indicator swap. These particular ones were frickin tight in the panel. So..... the next best option is pull the panel up (recommended with power off).
After a plug swap......
A300-600 ASM 79-30-00
Indicator Replacement AMM 79-33-21-04 (Different sub-chapter depending on whether GE or Pratt)