2002 Maxima Startup Issue (New Engine)

[Charlie Rock]

I am new to this forum and have a question regarding my 2002 Nissan Maxima SE, my mechanic recently changed the engine on my 5th Gen Max and is now unable to start the car with the car's key via the ignition.
He swapped the engine because of an engine knocking issue and is able to start the car under the hood through the starter but not through the key in the ignition.
Could this be an issue with the ignition or the computer not recognizing the new engine (sorry if I'm way off here but I just don't know all the particulars that can cause this issue) or possibly the key's chip not recognizing the new engine?
I also had a remote start switch which I informed him I had prior to his doing the swap. Any help would be appreciated.

[ezb57e]

A new engine will not cause the NATS system to deny starting.
If the NATS system was a problem, there would be a red warning lamp on the dash saying so, and the injectors would be disabled, so the car wouldn't start from under the hood either.
Your guy needs to look at the ignition switch/starter circuit.
ezb

[maxima2003cbrRR]

Did you ever figure out what the cause to your problem was I had the transmission replaced in my 2003 and it is doing the same thing now I can jump across the starter and it will start and run as long as ignition is in the on position but won't start using the key with out jumping across the starter any help would be greatly appreciated

[Charlie Rock]

Hi, sorry about the tardy reply but I am logging in for the first time in quite some time and didn't see your post until now.
Hopefully at this point you've already resolved your problem but in my case it turned out to be that the key's code had to be re-entered into the computer, it seems to have 'forgotten' the code and had to be re-programmed.