P1611 - FAULT CODE - OBD2

P1611 INFINITI, NISSAN: KEY ID DISCORD IMM-ECM

The immobilizer is an electronic device that is installed in vehicles to prevent the vehicle's engine from running unless the correct key is used. This device ensures that the vehicle is turned on after successful entry.

A microcircuit inside the key is activated by an electromagnetic field, which is responsible for inducing a current flow inside the key body. At the same time, this action emits a unique binary code that is sent to and read by the Engine Control Module (ECM). If the ECM determines that the encoded code is valid, it activates the fuel-injection sequence.

The P1611 OBDII diagnostic code is stored on Nissan and Infiniti vehicles when the result of the ID check between the immobilizer system unit and the ECM is negative. Because of this condition, system initialization is necessary.

How does the P1611 Fault Code work?

The energized immobilizer control module transmits a signal containing its unique value, which is received by the Engine Control Module. The ECM then compares this value with a value stored in memory, the code learned from the key.

If the value is correct, the ECM sends a randomly generated number to the immobilizer control module called a "challenge number". Both the immobilizer control module and the engine control module perform a "challenge number" calculation. If this calculation matches the engine control module, the fuel is activated. If either the immobilizer control module's unique value or the "challenge number" calculation is incorrect, the ECM will deactivate the fuel pump, or if new keys are needed, the immobilizer control module will need to be replaced.

• Check Engine lamp is on.
• The engine cannot be started.
• The motor is unstable.
• Low voltage.

The reasons why the DTC P1611 OBD2 code setting occurs are:

• The ignition key may not be programmed or have been damaged.
• The IMMU (Immobilizer Antenna) or BCM may be faulty.
• The Engine Control Module may be damaged.