Nissan NATS Explained: ECU and BCM Pairing, Used ECU Problems and When You Need a Virgin or Immo Off File

NATS (Nissan Anti-Theft System) links the key transponder, the BCM (body control module, called IMMU on older cars) and the engine ECU. Every start is a three-way handshake. Replace any one of the three without pairing and the car cranks without starting while the red key lamp flashes. This guide covers Nissan NATS ECU pairing on the models we see most: Qashqai, Juke, Micra, Note, X-Trail, Navara, Primera and Almera, plus the Renault-engined diesels.

The three generations

• NATS 2 / 3 (1990s–early 2000s): IMMU box behind the dash; ECU stores the code. Pairing with Consult II and the NATS PIN.
• NATS 5 (2002–2010): BCM handles the keys; ECU and BCM share the code. Consult III with the 4-digit PIN from the BCM label.
• NATS 5.x / 6 (Intelligent Key) (2007 onward): BCM, IPDM and ECU; 20-digit encrypted PIN calculated from the BCM code; Consult III+ registration.

Used engine ECU fitted

The used ECU carries the NATS code of the donor. Options:

1. Virgin file — resets the NATS block so Consult can register the ECU to your BCM. Standard route on the Bosch EDC17C84, EDC16C36/C41, Siemens SID305/SID310 and Denso units of the diesel range, and on the Hitachi petrol ECUs where supported.
2. Immo off — the ECU no longer asks the BCM. For swaps, dead BCMs and vehicles with an obsolete IMMU.
3. Cloning — if the original ECU still reads, copy its EEPROM into the donor; no registration needed.

Used BCM fitted

A used BCM brings its own keys and code. It must be virginised or the keys re-registered with the PIN of that BCM, then the ECU registered to it. Many no-start Nissans arrive with a used BCM “that should have worked” — it never does without the registration.

Reading the ECU

Diesel Nissans (1.5/1.6/2.0 dCi from Renault, 2.2/2.5 dCi YD22/YD25 with Denso) read on the bench with KTAG, Flex or New Trasdata; many also over OBD with KESS. Petrol Hitachi/Denso ECUs (HR16, MR20, QR25) are mostly bench/boot jobs. Save the full read and the label photo before anything else.

After the write

Virgin: run “NATS registration” or “ECU registration” in Consult with the PIN; the key lamp goes out and the engine starts. Immo off: starts immediately; the lamp may keep flashing. If the car still cranks only, check the crank sensor (a known failure on QR and YD engines) and the IPDM relay for the fuel pump.

Files

Browse the Nissan brand page for original, virgin and immo off files by ECU number (23710 xxxxx), or send your read via the file request form. Renault-engined models share files with Renault and Dacia under the same Bosch or Siemens number.