Oil Pressure

Started the day going to get a load of sod pulling it with 600 horsepower cummins oil pressure was 40 when I left home as the day went along oil pressure kept getting lower started pulling a mountain eventually it was down to 20 engine warning came on and restricted my Power shut the truck down for 10 minutes then restarted pressure came back up a little then came back down had sensor replaced didn't help anyone have any ideas what's going on

Did you change out the filters? That's the first thing I'd check.

How many miles on engine ? (worn out bearings) how long since last oil change ? ( old oil, lost Viscosity, Fuel dilution into engine ?) engine running Hot ? (not enough air going thru dirty Radiator ? ) worn out oil pump ? (clogged oil pickup, worn gears, stuck relief valve) ,, Time to get it FIXED before it Launches a ROD thru the Block,,,,, could be something cheap and simple, or might be time for an In Chassi Overhaul, don't know, but still Cheaper than a Rod thru the Block ,,,, $20,000

38000 miles

temperature 200-215 loaded pulling the mountain

Were your rpms low? Was your oil low? Overdue for oil/filter change? No no and no? Could be a blockage in the oil cooler or a weak or worn out oil pump, or???

Important thing with the Maxxforce engines is that parked regeneration function. If you don't do it, that potato in the tail pipe will clog up. You'll notice power loss, raised engine Temps (due to exhaust gasses not being able to get out )and eventually the computer will not allow the engine to restart. I'd definitely look into having the dpf cleaned.