Chain of ECM-IMMU


Table of contents

P1612 INFINITI Possible Causes

  • Faulty or not programmed ignition key
  • Faulty IMMU
  • Faulty Engine Control Module (ECM)

How do I fix code P1612 INFINITI?

  Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.

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 persists you have to have the dealer erase the code and reprogram the keys again.

Cost of diagnosing the P1612 INFINITI code

  The cost of diagnosing the P1612 INFINITI code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.

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.)

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Engine would not start

P1612 INFINITI Description

  An immobilizer is an electronic device fitted to an automobile which prevents the engine from running unless the correct key is present. This prevents the car from being hotwired after entry has been achieved.
The microcircuit inside the key is activated by a small electromagnetic field which induces current to flow inside the key body, which in turn broadcasts a unique binary code which is read by the automobile’s Engine Control Module (ECM). When the ECM determines that the coded key is both current and valid, the ECM activates the fuel-injection sequence.
The immobilizer function of the Infiniti Vehicle Immobilizer System (IVIS) or Nissan Anti-Theft System (NATS) consists of the following:
– NATS ignition key
– NATS antenna amp. located in the ignition key cylinder
– Body control module (BCM) or (IMMU)
– Engine Control Module (ECM)
– Security indicator lamp

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