KIA says:
"P1624 MIL request signal from TCM to ECM
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This is only a request from TCM to ECM to turn the MIL on. The fault code is stored in the TCM. The Freeze Frame Data is stored in the ECM under the P1624 request code. Be sure to retrieve freeze frame data before clearing code P1624 from ECM."

..meaning "tranmission control module has stored a code and send a signal to turn the check engine light ON. DO you have the check engine light(CEL, or MIL) ON ?

IN some cases....improperly seated gas cap or loss of fuel tank vacuum (hoses, sensor) have been linked to that flashing HOLD ...weird..but simple things first....