SPN 94 - FMI 3 (Fault Code 546)

Fuel Delivery Pressure Sensor Circuit - Voltage Above Normal or Shorted to High Source

Fuel Rail Pressure Sensor Circuit

Fault Code: 546
PID(P), SID(S): P94
SPN: 94
FMI: 3/3
Lamp: Amber

REASON: High signal voltage detected at the fuel rail pressure sensor circuit.

EFFECT: Engine may run rough, may stop running, may not start, or may be difficult to start.

Circuit Description:
The engine control module (ECM) provides a 5 volt supply and ground to the fuel rail pressure sensor using a dedicated sensor supply circuit. The pressure sensor delivers a fuel pressure signal to the ECM of the fuel rail. During engine operating conditions, the ECM commands and monitors the fuel rail pressure. If the fuel rail pressure exceeds or falls below commanded pressure, a fault will set.

Component Location:
The rail fuel pressure sensor is located on the bottom front corner of the integrated fuel system module (IFSM).

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 fuel rail pressure signal voltage was out of range high.

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, and leave the key in the ON position 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:
• Open return circuit in the harness, connectors, or sensor
• Signal circuit shorted to sensor supply or battery voltage.
• Sensor supply circuit shorted to battery voltage.
• A malfunctioning fuel rail pressure sensor

Read More:
SPN 94 - FMI 4 (Fault Code 547)
SPN 558 - FMI 4 (Fault Code 551)


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