Fault Codes/Winco/129D-4Winco129D-4UnclassifiedCoolingWhat This Code MeansSubstitute value is taken for Oxi Cat temperature upstream sensorPossible Causes•Defect in the electrical signal of the Oxi Cat temperature upstream sensorRelated Winco Fault Codes251-1F 594 31252-1F 623 6129D-3A6-298-2 157 0A6-E69-4 108 3A8-369-3 105 4A8-466-15 105 3AC-3Browse all Winco fault codes→ASK RUDY ABOUT THIS FAULTGet a diagnosis walkthrough for 129D-4 on your specific Winco unit — cited to the OEM manual, not a forum guess.TRY IT FREE