Fault Codes/Rehlko/21247Rehlko21247UnclassifiedGeneralWhat This Code MeansUnit Failed to Report HeartbeatRelated Rehlko Fault Codes21256516281 1520771516284 172007516600 32006516600 42005516663 02004516663 31Browse all Rehlko fault codes→ASK RUDY ABOUT THIS FAULTGet a diagnosis walkthrough for 21247 on your specific Rehlko unit — cited to the OEM manual, not a forum guess.Your question about 21247GET THE ANSWERFree account required — we'll bring your question with you.