The 1613 indicates there is a malfunction of the ECM internal circuit of IMMU communication line.
Here is what the manual indicates:
2003 Nissan-Datsun Altima V6-3.5L (VQ35)
Vehicle ALL Diagnostic Trouble Codes ( DTC ) Testing and Inspection P Code Charts P1613
see pic 1
Self-diagnostic results: "ECM INT CIRC-IMMU" displayed on CONSULT-II screen
1. Confirm SELF-DIAGNOSTIC RESULTS "ECM INT CIRC-IMMU" displayed on CONSULT-II screen. Ref. Part No. B.
2. Replace ECM.
3. Perform initialization with CONSULT-II.
For initialization, refer to "CONSULT-II OPERATION MANUAL IVIS/NVIS".
I have to be honest, the key itself could be the issue. If you use an unregistered or damaged key and try to start it five or more times with a bad key, it will lock the system.
If you have a spare key, do this. Disconnect the battery for about an hour. Reconnect the battery and see if it starts using a known good key.
Let me know what you find.
Sunday, November 29th, 2020 AT 9:46 PM