Truck Repair: N14 CELECT Trouble Codes, n14 cummins engine, drive oil

Question
My dad's 1991 9400 Series International with the N14 Cummins engine quit today while I was driving it and gave us an 'out of fuel' symptom.  We tried a new fuel filter and the old one looked good, no water in it.  Then we thought the electronic soilenoid on the fuel pump may be bad and had that on/off several times, sometimes it would 'click' and sometimes it wouldn't.  It sometimes will start but repeatedly dies.  I checked the CELECT trouble codes while I was waiting for him to arrive with the new fuel filter and it flashed a '1', '2', '1' code.  Only 1 code, no second code.  After we had messed around for a couple hours with everything else I re-checked the trouble codes and got nothing.  Solid 'on' condition of both the 'Enging Warning' and 'Engine Stop' lights which the book says indicates no trouble codes.  The truck still does the same thing, starts and dies, starts and dies.  Do you know what that trouble codes means or perhaps what may be the problem?  Thank you very much.

Answer
Fault 121 & 115 are EPS sensor faults.Check the EPS for proper OHMN reading.Should be 1000-2000 OHMN.The sensor is located between accy drive & oil pump.There are 2 coils in the sensor(4 wires).Should be the 2 inside wires is one coil & the 2 outside wires are the other coil.