CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 428

Water-in-Fuel Indicator 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 Indicator 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.

ISX – Water-in-Fuel Sensor Circuit
ISM – Water-in-Fuel Sensor Circuit

Circuit Description

The water-in-fuel sensor is attached to the fuel filter. The electronic control module (ECM) provides a 5-VDC 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 OEM supplied suction fuel filter. The OEM supplied fuel filter is located on the intake side of the engine.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes

The ECM detects that the sensor signal voltage is above 4.95-VDC for one second.

Action Taken When the Fault Code is Active

  • The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Shop Talk

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe™ Online for applicable fixes to the calibration stored in the ECM. If necessary, calibrate the ECM. Refer to Procedure 019-032 in Section 19.

Possible causes for this fault code include:

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

Refer to Troubleshooting Fault Code t05-428

Last Modified:  09-Jul-2010