always worth replacing both the oil pressure sensors before you do anything else, from the symptoms it sounds like the black/brown low pressure sensor with the blue wire is at fault. Check the wiring for damage, and the oil pressure warning control board in the clocks can sometimes be faulty also.
If the oil pump was on the way out you would get the oil pressure warning light and a buzzer sound over 2k rpm, the white sensor with the yellow wire is reponsible for this. To test its working disconnect the yellow wire and rev the engine over 2k. If the buzzer comes on that means the high pressure warning switch is working and that your oil pump is probably fine.