128:F02 SID251_A Fault code

[DVT873]

An old NEXIQ (2008) Fault code guide I have calls this out as "Unswitched Battery Supply Circuit - Low Voltage" so maybe a bad connection between battery and ECM? Insite would be best. On age call the S/N on the sticker into Cummins and they should be able to break it down and also tell you if it was with or without the ECM.