P1612 - FAULT CODE - OBD2

P1612 INFINITI, NISSAN: CHAIN OF ECM-IMMU

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 decrease in car theft.

Modern immobilizer systems use rolling codes through which it is possible to prevent the key or controller code from being copied. The key is activated by an internal microcircuit activated by an electromagnetic field. This electromagnetic field induces voltage flowing in the key that produces or emits a binary code read by the Engine Control Module (ECM). If this controller detects that the key is valid, the injection sequence is allowed.

When DTC P1612 OBD2 is set, it is because the immobilizer has experienced a wrong operation. Specifically, on Nissan vehicles, this code signals that the ECM has not received the ID signal or binary code that allows the engine to start.

• Check Engine light illuminated.
• The engine does not start.

OBDII fault code P1612 is set by one or more of the following reasons:

• The ignition key may have programming errors or damage.
• The Immobilizer Antenna (IMMU) could be faulty.
• The ECM could have inconsistencies.

To troubleshoot the P1612 OBD2 diagnostic code, consider this:

• Start the diagnosis by consulting the TSB.
• By using an automotive scanner, check if other fault codes are stored. If so, repair the codes following the order shown by the scanner.
• Keep the vehicle's battery disconnected for 30 minutes. After this, start the engine using a correctly programmed key. If the code is displayed, it is necessary to reprogram the key.