Water in Fuel Indicator Malfunction

Water in Fuel Indicator Malfunction

Diagnostic Instructions

* Perform theDiagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



Circuit/System Description

If there is water in the fuel system, the water in fuel sensor/switch will close and produce a low voltage on the signal circuit. When the engine control module (ECM) detects a low signal from the water in fuel sensor the ECM will send a serial data message to the instrument panel cluster (IPC). The IPC will then illuminate the WATER IN FUEL SERVICE REQUIRED message in the driver information center (DIC).


Reference Information
Schematic Reference

Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* Fuel System Description (Fuel System Description)
* Indicator/Warning Message Description and Operation (Indicator/Warning Message Description and Operation)

Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information.


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the water in fuel sensor.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal B and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, observe the Water In Fuel Sensor parameter. The parameter should display No Water.

• If parameter does not display No Water, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. The Water In Fuel Sensor parameter should display Water.

• If a 3A fuse opens and the Water In Fuel Sensor parameter displays No Water, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
• If the Water In Fuel Sensor parameter displays No Water and the 3A fuse did not open, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the water in fuel sensor.



Component Testing

1. Remove the water in fuel sensor.
2. Connect a DMM between terminal A and terminal B of the sensor harness connector.
3. Measure the resistance of the sensor while moving the float up and down the float barrel.
4. The resistance should switch from less than 0.5 ohm and 0.L.

• If the resistance did not change, replace the water in fuel sensor.




Repair Instructions

Perform theDiagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Water in Fuel Indicator Sensor Replacement ()
* Control Module References (Programming and Relearning) for the ECM replacement, setup, and programming