P1612 – Chain of ECM-IMMU (Nissan/Infiniti)

By Brian Jones (Contact Me)
Last Updated 2019-02-22

Code	Fault Location	Probable Cause
P1612	P1612 – Chain of ECM-IMMU (Nissan/Infiniti) (Buy Part On Amazon)

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Manufacturer Specific Definitions for P1612

Make	Fault Location
Audi	Engine control module (ECM) - coding
Buick	Loss Of IPM Serial Data
Cadillac	Instrumentation control module
Chevrolet	Loss Of IPM Serial Data
Chrysler	Throttle position (TP) control module malfunction
Citroen	SBDS Interactive Codes
Daewoo	Ventilation Sol V/V -Elec. Sys
Dodge	Engine control module (ECM) -supply voltage
Freightliner	Engine control module (ECM) -supply voltage
Gm	Loss Of IPM Serial Data
Hyundai	Ventilation Solenoid Valve Electrical.
Infiniti	Immobilizer control module/engine control module (ECM) communication – malfunction
Mahindra	Main Relay Stuck
Nissan	Immobilizer control module/engine control module (ECM) communication – malfunction
Opel	Immobilizer control module - no / incorrect signal
Peugeot	SBDS Interactive Codes
Volvo	Electronic throttle system (ETS) – no signal
Volkswagen	Engine control module (ECM) - coding

What Does Code P1612 Mean?
What are the common causes of code P1612?
What are the symptoms of code P1612?
How difficult is it to repair code P1612?
How do you troubleshoot code P1612?
Codes Related to P1612
Get Help with P1612

What Does Code P1612 Mean?

This code signifies an interruption of communication between the ECM and the IMMU. As a result, the engine will not start. Often, it’s simply related to using the wrong or damaged key while other instances might point to an issue with the ECM or immobilizer.

Nissan and Infiniti both use anti-theft and immobilizer systems with this function. Components consist of:

Engine Control Module (ECM)
Security indicator lamp
NATS antenna amp
Body control module
NATS ignition key

What are the common causes of code P1612?

Occasionally, this occurs during the key registration procedure and the code remains stored. More commonly, this code is triggered because of an unregistered key that’s used five times consecutively.

Other known causes include:

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

What are the symptoms of code P1612?

Engine Light is on
Engine will not start

How difficult is it to repair code P1612?

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

How do you troubleshoot code P1612?

First, look at your key. If it is the wrong key or is damaged, you need to get a new one from the dealer.
Disconnect the battery for 30 minutes and then attempt to start the engine again.
Check for a blown fuse.
Check the voltage between the connector and body ground to see if there’s an issue in voltage with the immobilizer.
Check the voltage between the terminal and body ground. Make sure the ignition switch is turned on. This indicates an issue with the immobilizer.
To look for an issue with the ECU, you would need special equipment to check the condition.

Codes Related to P1612

P0606 PCM / ECM Processor Fault
P1570 Engine Control Module Immobilizer Active
P1610 NISSAN – Lock Mode
P1611 NISSAN – Key ID Discord IMM-ECM
P1613 NISSAN – ECM INT CIRC-IMMU
P1614 Chain of IMMU-KEY
P1615 NISSAN – NVIS Difference of Key

Often, P1612 and P1614 will present themselves together. This is common and often indicates a problem larger than with the key itself.

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