Cummins ISB4.5 CM2150 Fault Code: 3563 PID: SPN: 5491 FMI: 4 Aftertreatment Diesel Exhaust Fluid Line Heater Relay – Voltage Below Normal or Shorted to Low Source.

Posted by PerDiezel Solutions on January 20, 2026

Circuit Description
The aftertreatment diesel exhaust fluid line heater relay provides the power supply to line heaters 1, 2, and 3. It is controlled by the aftertreatment diesel exhaust fluid controller.

Component Location
The aftertreatment diesel exhaust fluid line heater relay location is original equipment manufacturer (OEM) dependent. Refer to the OEM service manual for more information.

Conditions for Running the Diagnostics
This diagnostic runs at key off. The fault will be active at the next key-on event.

Conditions for Setting the Fault Codes
The aftreatment diesel exhaust fluid controller detects that the voltage in the diesel exhaust fluid line heater relay circuit is below a calibratible value.

Action Taken When the Fault Code is Active
-The electronic control module (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
-The fault code status displayed by the INSITE electronic service tool 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 ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
-For OBD engines, the ECM will turn off the MIL after 3 consecutive trips where the diagnostic runs and passes.
-The “Reset All Faults” command in the INSITE electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications

Possible Causes
-Short to ground in the aftertreatment diesel exhaust fluid line heater relay circuit.
-Short to ground in the aftertreatment diesel exhaust fluid controller harness.
-Malfunctioning aftertreatment diesel exhaust fluid controller.

Cummins ISB4.5 CM2150 Fault Code: 3562 PID: SPN: 5491 FMI: 3 Aftertreatment Diesel Exhaust Fluid Line Heater Relay – Voltage Above Normal or Shorted to High Source.

Cummins ISB4.5 CM2150 Fault Code: 3561 PID: SPN: 3361 FMI: 5 Aftertreatment Diesel Exhaust Fluid Dosing Unit – Current Below Normal or Open Circuit.

Cummins ISB4.5 CM2150 Fault Code: 3559 PID: SPN: 3361 FMI: 4 Aftertreatment Diesel Exhaust Fluid Dosing Unit – Voltage Below Normal or Shorted to Low Source.

Cummins ISB4.5 CM2150 Fault Code: 3558 PID: SPN: 3361 FMI: 3 Aftertreatment Diesel Exhaust Fluid Dosing Unit – Voltage Above Normal or Shorted to High Source.

Cummins ISB4.5 CM2150 Fault Code: 3557 PID: SPN: 3360 FMI: 2 Aftertreatment Diesel Exhaust Fluid Controller – Data Erratic, Intermittent, or Incorrect.

Cummins ISB4.5 CM2150 Fault Code: 3555 PID: SPN: 1081 FMI: 9 Engine Wait to Start Lamp – Abnormal Update Rate

WARNING!