Cummins ISB4.5 CM2150 Fault Code: 4642 PID: SPN: 97 FMI: 0 Water-in-Fuel Indicator – Data Valid But Above Normal Operating Rage – Moderately Sever Level.

Posted by PerDiezel Solutions on January 20, 2026

Circuit Description
The water-in-fuel sensor is attached to the fuel filter. The engine control module (ECM) provides a 5 volt reference signal to the water-in-fuel sensor. When the water collected in the fuel filter covers the sensor probes, the water-in-fuel sensor pulls the 5 VDC reference voltage to ground, indicating high water accumulation in the fuel filter.

Component Location
The water-in-fuel sensor is integrated into the bottom of the original equipment manufacturer (OEM) supplied suction fuel filter.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes
The ECM detects water in fuel for an extended period of time.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
-To validate the repair, perform a key cycle, start the engine, and let it idle for 1 minute.
-The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
-The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
-The “Reset All Faults” command in INSITE™ electronic service tool can be used to clear active and ianctive faults, as well as extinguish the MIL for On-Board Diagnostics applications.

Shop Talk
Water in the fuel can do extensive damage to the fuel system, due to the tight tolerances of the fuel system components. The engine will be derated for protection purposes.

The fuel filter must be drained immediately.

If this fault code is active and there is no water in the fuel filter, a malfunctioning water-in-fuel sensor is a likely cause.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

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WARNING!