Fault Codes/Cummins/252Cummins252UnclassifiedGeneralWhat This Code MeansI/O MODULE LOST 252 warning displayedPossible Causes•Intermittent data link between the I/O Module and the Base boardRelated Cummins Fault Codes254285245286239379238418236425234426Browse all Cummins fault codes→ASK RUDY ABOUT THIS FAULTGet a diagnosis walkthrough for 252 on your specific Cummins unit — cited to the OEM manual, not a forum guess.Your question about 252GET THE ANSWERFree account required — we'll bring your question with you.