F-150 7700 Oil Guage

I have a 2002 F-150 XLT, 7700, 5.4L, extended cab, short bed with 76K miles. The oil pressure guage is intermittently dropping to zero and the adjacent oil lite comes-on. So far this has happened only when the engine is cold. once the engine warms, everything goes back to normal. I have plenty of oil in the pan.
I assume the sensor or wiring is bad, but would like to hear if others have had this problem before I start trying to find the sensor and replacing things.

Thanks,
John

Install a mechanical gauge in place of the sending unit and see what pressures you are actually running. If mechanical gauge stays steady, look at the sending unit being bad. It is located next to the oil filter.

Try cleaning up the electrical connector on the pressure sender with a bit of fine sandpaper. Make sure the electrical contacts are nice and shiney.

If the problem persists, install a mechanical oil pressure gauge in place of the original sender, just to verify that the problem is the stock gauge and not the engine itself.