CM870 and ISX Engines – FAULT CODE 428

Water-In-Fuel Sensor Circuit – Voltage Above Normal or Shorted to High Source


Fault Code: 428
PID: P097
SPN: 97
FMI: 3/3
LAMP: Amber

Water-in-Fuel Sensor Circuit – Voltage Above Normal or Shorted to High Source. High voltage detected at the water-in-fuel circuit.

None on performance. No water-in-fuel warning available.

Water-In-Fuel Sensor Circuit

Circuit Description

The water-in-fuel sensor is attached to the suction-side fuel filter. The water-in-fuel sensor sends a signal to the Electronic Control Module (ECM) when a set volume of water has accumulated in the fuel filter. The water-in-fuel circuit contains two wires: a return and a signal wire.

Component Location

The water-in-fuel sensor is integrated into the bottom of the Original Equipment Manufacturer (OEM) supplied fuel filter. Refer to the OEM troubleshooting and repair manual for location.

Shop Talk

Beginning with Engine Serial Number (ESN)14039654, the temperature sensor return circuit was separated from the pressure sensor return circuit. For ESNs prior to this and with engine wiring harness Part Number 3682854, refer to the Common Pressure/Temperature Sensor Return Circuit above. For this ESN and greater or for any other engine wiring harness part number, refer to the Separate Pressure/Temperature Sensor Return Circuit above.

The water-in-fuel sensor shares return wires in the engine harness with other sensors. An open return can cause multiple fault codes to be active. Before troubleshooting Fault Code 428, check for multiple fault codes.

Possible causes for this fault code include:

  • Open return or signal circuit in the harness, connectors, sensor, or ECM.
  • Signal wire shorted to sensor supply or battery voltage.

Refer to Troubleshooting Fault Code t05-428

Last Modified:  01-Sep-2010