when going slow or just idling mine drops to zero randomly
found a replacement for cheap

New 98 12V Cummins Oil Pressure Switch ... $35.... awesome

CUMMINS OIL PRESSURE SENSOR ('94-'98, 12V)-Dodge Cummins Diesel Truck Accessories – Geno’s Garage
CUMMINS OIL PRESSURE SENSOR ('94-'98, 12V)-Dodge Cummins Diesel Truck Accessories – Geno’s Garage
Dodge Cummins Diesel Truck Accessories – Geno’s Garage

 

my stock one is screwed up we broke the sensor do a pump swap so i put a new one in an now doesnt work right. so i bought a mechanical oil gauge and installed it last night. holds 50 psi idling and rev it up goes up to 75 or more. havent drove it yet to see what it does

 

pretty much all the gauges in the stock dash cluster are a guessing game. the best thing to do is to get a alternate gauge set up.

 

If your gauge and sender and wiring check out ok ( Best way is to remove sender and install a mechanical gauge and run it into the cab for testing/comparing) If that is all working properly, the oil bypass valve is most likely your problem

 

wheres the oil bypass valve

 

It will be located either behind the power steering pump or the fuel heater depending on where they wanted to drill it at the factory (all in the same area). Mine was infront of the fuel heater.

To replace it on a 98 you need a 1-1/16" Oil Pressure Sender Socket (long deepweld) for the new sensor. Advanced Auto carries it. The old one you just break off the plastic part and use a regular 1-1/16" socket.

 

it's mounted in the oil cooler at the top, just forward of the oil filter head. I tried to 'google' it so i could post a pic for you, but the only thing that shows up is oil bypass filter kits, sorry.

 

Im having the same problem when I stop. Anyone know where I can buy the oil sensor?

 

Sensors-Dodge Cummins Diesel Truck Accessories – Geno’s Garage