LOCKNUT 0964407 - Caterpillar

Which Generate This Code:The Electronic Control Module (ECM) detects the following conditions:390(1)
The fuel filter differential pressure switch is open for one hour.
The engine has been running for at least three minutes.Note: The fuel filter differential pressure switch will open at 103 14 kPa (15 2 psi).390(2)
The fuel filter differential pressure switch is open for four hours.
The engine has been running for at least three minutes.Note: The fuel filter differential pressure switch will open at 103 14 kPa (15 2 psi).System Response:390(1)The check engine lamp will illuminate while this event code is active. The event code will be logged once the fuel filter differential pressure switch is closed for five minutes.Note: The fuel filter differential pressure switch will close at 83 kPa (12 psi).390(2)The check engine lamp will illuminate while this event code is active. The event code will be logged once the fuel filter differential pressure switch is closed for five minutes.Note: The fuel filter differential pressure switch will close at 83 kPa (12 psi).390(1)There are no performance effects.390(2)The ECM will derate power by 35 percent at 17.5 percent per second.
The fuel filter may need to be replaced. Replace the fuel filter. Refer to the Operation and Maintenance Manual.
The fuel lines may be restricted. Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.
There may be a problem with the fuel filter differential pressure switch.Test Step 1. Perform the following diagnostic procedure: Fuel Filter Differential Pressure Switch Circuit - TestResults:
OK - STOP