ARM AS- 7C7772 - Caterpillar

Table 1
Event Code    
Code and Description    Conditions which Generate this Code    System Response    
E390(1) Fuel Filter Restriction     The difference between the filtered fuel pressure and the unfiltered fuel pressure is greater than the trip point pressure. The delay time for this event code is one hour.     The code is logged.    
E390(2) Fuel Filter Restriction     The difference between the filtered fuel pressure and the unfiltered fuel pressure is greater than the trip point pressure. The delay time for this event code is four hours.     The engine ECM will derate engine power. The code is logged.    Probable Causes
Fuel filter element
Electrical connectorRecommended Actions
Fuel Filter Element
Replace the fuel filter element.
Restart the engine.
The delay time for the E390(1) event code is one hour. If the event code becomes active after recently changing the fuel filter, the problem may be electrical. Refer to Troubleshooting, "Fuel Filter Differential Pressure - Test" for the procedure to troubleshoot the circuit.Electrical Connector
Check all electrical connectors between the ECM and the sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".