No start condition solved! After 4 weeks of cranking but not turning over and no check engine light, I thought it was fuel pump, low fuel pressure, fuel pump relay, crankshaft position sensor, security system etc.

It made no sense when one day the car started up and was not down on power. Was nearly questioning my sanity when I took the code reader out tonight, knowing there was no CEL but P1615 was there the whole time! Car thought it was trying to be started by an unregistered key!

I couldn't find much online anywhere that was very helpful so hopefully the next person with this issue stumbles across this thread.

Most likely the NATS antenna is the issue, however I am going to do as many others suggested and just flip the key around, lock/unlock doors, unlock door with key and it should work. I've been able to start the car several times in a row successfully at this point.

In addition to those fixes listed above, apparently unhooking the negative battery cable will make the car forget it was being started with an "unregistered key" (in it's mind) and should give you another go.

 

Thanks! Filed in the "if this ever happens to me file."

 

Fyi sometimes the NATS antenna fails also.

Good to hear it's fixed tho!

 

THANK YOU SIR!!!!!

My situation was similar, sometimes it would crank, sometimes it wouldn't. Car finally just wouldn't turn over one night. Read this thread, ran to the garage, stuck the key in the door to unlock it. Got in the car, stuck the key in the ignition but still didn't turn over. Then I flipped the key over stuck it back in the ignition and bam!! back in action. Car started up and ran like a champ.

Obviously something's wrong, but still, nice little trick to know until you can fix the real issue.

 

This happens to my car like once a year. All I do is get in close all the doors, lock and then unlock the car with the key fob. Wait like 5 seconds and start the car Good to go