[joey]

Here is what the service manual says are the possible causes of P0520.
All the Diagnostic Testing to find the cause is too complicated for most of us girls, and we don't have the tools either. Dealer is your best bet to find the fix.

(G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
RESISTANCE (G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT
(G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN (F856) 5-VOLT SUPPLY CIRCUIT
(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE (K900) SENSOR GROUND CIRCUIT
ENGINE OIL PRESSURE SENSOR
PCM

While pulling fuse 11 cleared the codes, I believe some codes may return if the problem occurs 2 to 3 times in a row. You may need to drive/start-restart the car a few more times to be sure the codes do not return.