About a week agooooooooo, my max slowly started after 3 attempts....I pulled the 1612 NATS immobilizer code and cleared it without any problems since, but I feel like i'm in a ticking time bomb now . I do have a Viper remote start/alarm system installed which has been working flawlessly over the past 3yrs. When install, the original key with chip was placed inside some module, and I've been using a chipless key copy to drive around with. Is a trip/tow to the stealership my only option?

 

The key you are using may somehow be developing a problem or more likely the NATS antenna system may be going out and not always sensing the chip in the key.

P1612 Chain of ECM-IMMU

Possible causes
- Faulty or not programmed ignition key
- Faulty IMMU
- Faulty Engine Control Module (ECM)

Tech notes:
This code is usually triggered when a not registered or damaged key is used to start the engine. When the starting operation is carried out five or more times consecutively with the same unregistered key, the system will lock.

If the problem occurs try disconnecting the car battery for about 30 minutes and then try starting the engine with a known registered key. If the problem persist you have to have the dealer erase the code and reprogram the keys again.

When is the code detected?
Communication impossible between ECM and IMMU (In rare cases, “CHAIN OF ECM-IMMU” might be stored during key registration procedure, even if the system is not malfunctioning.)

 

Ok so I've gone this long without the p1612 immobilizer code giving me any problems until today. Something told me to check the battery voltage, and behold a reading of 12.1 volts after the car had been sitting for over 12hrs. I jumped the car without any problems, went to AZ where they tested the battery and confirmed it was bad. So I got a brand new free optima yellow top 3months before warranty expired, and i'm hoping this will solve the problem, but maybe this is wishful thinking....we'll see