Well, I'd start by reconnecting the aux fan. I don't really see how that's linked, unless they're saying that the engine overheats that much with it disconnected, but hey...

Next, I'd replace the oil pressure sensor.

If it persists, I'd be suspicious of the oil pump or another oiling problem. Are your revs dropping more than usual? Thicker oil might help if the issue is a weak oil pump.

I definitely would NOT be commuting in it until I figured out if it's actually oiling the engine properly or not. These engines will go some time with zero oil pressure under gentle conditions, but not that long.

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2011 M3
2006 Sierra 2500HD 4WD LBZ/Allison
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1990 325is
1989 M3 S54B32

Hers:
1989 325iX
1996 911 Turbo