SPN 97 - FMI 4 (Fault Code 429)

Water in Fuel Indicator Sensor Circuit - Voltage Below Normal or Shorted to Low Source

Water-in-Fuel Indicator Sensor Circuit

Fault Code: 429
PID(P), SID(S): P97
SPN: 97
FMI: 4/4
Lamp: Amber

REASON: Low voltage detected at the water-in-fuel circuit.

EFFECT: None on performance.

Circuit Description:
The water-in-fuel sensor is in 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 down, 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.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the water in fuel sensor signal voltage was less than 0.05-VDC for 1 second.

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 the recommended Cummins® electronic service tool or equivalent 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 the recommended Cummins® electronic service tool or equivalent can be used to clear active and inactive faults.

Shop Talk:
Possible causes of this fault code include:
• Signal circuit shorted to ground in the harness, sensor, or connector.
• Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

Read More:
SPN 558 - FMI 2 (Fault Code 431)
SPN 558 - FMI 13 (Fault Code 432)


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