Cummins ISB4.5 CM2150 Fault Code: 442 PID: 168 SPN: 168 FMI: 0 Battery 1 Voltage – Data Valid but Above Normal Operating Range – Moderately Severe Level.

Posted by PerDiezel Solutions on January 20, 2026

Circuit Description
The electronic control module (ECM) receives constant voltage from the batteries through the unswitched battery wires that are connected directly to the positive (+) battery post. There is one 30-ampere fuse in the unswitched battery wire to protect the original equipment manufacturers (OEM) harness. The ECM receives switched battery input through the vehicle keyswitch wire when the vehicle keyswitch is turned ON. The battery return wires are connected directly to the negative (-) battery post.

Component Location
The ECM is connected to the battery by the OEM harness. This direct link provides a constant power supply for the ECM. The location of the battery will vary with the original equipment manufacturer (OEM). Refer to the OEM troubleshooting and repair manual for battery location.

Not Applicable

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 ECM detects that the main battery supply voltage is greater than +36-VDC.

Action Taken When the Fault Code is Active
-The ECM logs the fault code and illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
-The ECM will turn off the fault code and amber CHECK ENGINE light, and the fault code will go inactive immediately after the battery voltage drops below +36-VDC.
-This fault code can also be cleared with INSITE™ electronic service tool.

Shop Talk
This fault code is logged when the ECM battery supply voltage exceeds +36-VDC.

Possible Causes
-Faulty alternator or regulator that is overcharging the system
-Batteries connected in series instead of parallel
-Incorrect jump-starting procedure.

Cummins ISB4.5 CM2150 Fault Code: 441 PID: 168 SPN: 168 FMI: 1 Battery 1 Voltage – Data Valid but Below Normal Operating Range – Moderately Severe Level.

Cummins ISB4.5 CM2150 Fault Code: 436 PID: 111 SPN: 105 FMI: 2 Intake Manifold 1 Temperature – Data Erratic, Intermittent, or Incorrect.

Cummins ISB4.5 CM2150 Fault Code: 435 PID: 100 SPN: 100 FMI: 2 Engine Oil Rifle Pressure – Data Erratic, Intermittent, or Incorrect.

Cummins ISB4.5 CM2150 Fault Code: 429 PID: 97 SPN: 97 FMI: 4 Water-in-Fuel Indicator Sensor Circuit – Voltage Below Normal or Shorted to Low Source.

Cummins ISB4.5 CM2150 Fault Code: 428 PID: 97 SPN: 97 FMI: 3 Water-in-Fuel Indicator Sensor Circuit – Voltage Above Normal or Shorted to High Source.

WARNING!