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Error Code P1612 – Symptoms, Causes and Solutions

The immobilizer is part of the car’s security system. This device prevents the engine from starting without the use of the transponder key, thus achieving a significant reduction in car thefts. Error Code: P1612.


Modern immobilizer systems use rolling codes through which it is possible to prevent the copy of the key code or the controller. The key is activated by an internal microcircuit activated by an electromagnetic field.

This electromagnetic field induces a voltage that flows in the key and produces or emits a binary code that reads the engine control module (NDE). If this driver detects that the key is valid, the injection sequence is allowed.

Error Code: P1612

When the DTC P1612 OBD2 is set, it is because the immobilizer has experienced incorrect operation. Specifically, in the Nissan vehicles this code indicates that the ECM has not received the identification signal or binary code that allows the engine to start.

Reads: P0112 OBD Error Code – Intake Air Temperature Sensor 1 Low Input Circuit

What does the P1612 code mean?

This code means an interruption of communication between the NDE and the IMMU. As a result, the engine does not start. Often it is simply related to using the wrong or damaged key, while other cases could point to a problem with the ECM or immobilizer.

Both Nissan and Infiniti use anti-theft systems and immobilizers with this feature. The components consist of:

  • Engine control module (ECM)
  • Safety indicator lamp
  • NATS antenna amplifier
  • Body control module
  • NATS Ignition Key

What are the common causes of code P1612?

Occasionally, this occurs during the procedure. key registration and the code remains stored. Most commonly, this code is activated due to an unregistered key being used five consecutive times.

Other known causes are:

  • Open circuit in the battery voltage line of the IMMU circuit
  • Open circuit in ignition line of IMMU circuit
  • Open circuit in the ground line of the IMMU circuit
  • Open circuit in communication line between ECM and IMMU
  • Short circuit between the communication line between the ECM and IMMU and the battery line
  • Short circuit between the ECM and IMMU communication line and ground line
  • faulty IMMU
  • Defective ECM

What are the symptoms of code P1612?

  • The engine light is on
  • The motor does not start

Is it difficult to fix the P1612 code?

There is no way to reprogram the key without dealer tools. If it is a problem with a loose connection, once the fault is found, repairing it only takes a few seconds.

How do you fix the P1612 code?

  • First, look at your key. If it is the wrong key or it is damaged, you will need to get a new one from the dealer.
  • Disconnect the battery for 30 minutes and then try starting the engine again.
  • Check for a blown fuse.
  • Check the voltage between the connector and body ground to see if there is a voltage problem with the immobilizer.
  • Check the voltage between the terminal and body ground. Make sure the power switch is on. This indicates a problem with the immobilizer.
  • To look for a problem with the ECU, special equipment is needed to check the condition.

Questions and answers

Ask: I am getting a p1612 code-an incorrectly coded engine control module. I swapped a 2000 Jetta AEG Auto engine into my 99 Beetle AEG 5sp and now I am getting this code

For all I know, this code could have been floating around before the change… I have no way of knowing.

My question is: how can I find out why I’m getting this code and if I should worry about fixing it?

Answer: Have you ever made a peanut butter and jelly sandwich and ran out of peanut butter halfway through and had to grab more from another jar?

That’s what you have here. It’s all the same, but you know the difference. You need a vag com to “introduce” the 2 new parts together. shaking hands if you will. If you don’t care about the CEL I wouldn’t worry about it.

Answer: Sorry, I should have given more information. vagcom is what gives me this code I just don’t know how to fix it using. Is there a step-by-step out there?

And especially curious about what still tells you it’s a different engine. I have swapped the entire original engine onto the new Jetta engine now except the cam sensor maybe? and possibly the alternator….I don’t remember.

All accessories, coil packs, sensors, etc. are original to the car. I’m leaning towards maybe someone who changed the ECU years ago before I got it.

If you want to know other articles similar to Error Code P1612 you can visit the category Fault Codes.


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