Your situation could also be related to the grounding of the sensor.  An intermittent ground could possibly cause zero readings.

 

Mike Easley

 

I am always suspicious of sensors, wiring and connectors.  After writing, we returned to the hangar after pulling the engine, connected a compressed air hose to the EI oil pressure sensor on the firewall, and fussed.  No problems, indicated pressure tracked the air pressure regulator.  Then we had some aggressive wiggling of sensor, wiring, connectors, and wire bundles.  Rock solid, no evidence of intermittent  connection.

 

This coupled with the fact that hitting the brakes during taxi causing oil pressure dips suggests it is not instrumentation, but a real oil pressure problem.  Pan comes off for a look tomorrow, at the engine shop.

 

Fred