IAW 5NR2 Immo Off: Magneti Marelli ECU Solution for Renault Clio II, Kangoo and Twingo

The Magneti Marelli IAW 5NR2 family (5NR2.C2, 5NR2.C5, 5NR2.C6 and the 5NR3) runs the 1.2 16v D4F engine in the Renault Clio II phase 2, Kangoo, Twingo II and some Dacia Logan versions. These cars are now 15–20 years old, the UCH body computers fail regularly and keys get lost — so the immo off request for the 5NR2 is one of the most frequent in our shop.

Identify the exact version

The label on the ECU shows IAW 5NR2.Cx followed by a Renault part number (8200 xxx xxx). The C2, C5 and C6 variants have different software and the file is not interchangeable. If the label is unreadable, read the ECU and send us the file; the version is stored inside.

What immo off does on this ECU

The immobilizer code on the 5NR2 is stored in the ECU’s memory and compared with the code the UCH sends over the immobilizer line. The immo off file removes that comparison: injection and ignition are released without waiting for the UCH. Everything else — maps, idle control, diagnostics — stays as it was. This is a permanent solution for a dead UCH, a lost-key situation or a used ECU that cannot be paired with Clip.

Reading and writing

The IAW 5NR2 uses a Motorola HC12 processor. Reading over OBD is possible with KESS V2 on many units, but the reliable path is on the bench: KTAG or Flex in BDM/bench mode read and write the full flash and the EEPROM in a few minutes. A dedicated programmer such as UPA or XPROG also works if you are used to it.

1. Remove the ECU, connect the bench harness and a stable 12 V supply.
2. Read and save the full flash + EEPROM.
3. Compare the software identification with the product page.
4. Write the immo off file, verify, refit and start the car.

After the flash

The engine starts with any cut key. Because the UCH still controls the central locking and the dashboard immobilizer lamp, the lamp may keep flashing when the ignition is off; this is cosmetic. If you later replace the UCH and want the immobilizer back, write the original read.

Frequently seen problems

• Crank, no start after the write — wrong variant (C2 file on a C5 unit) or the injectors’ power relay is also controlled by the UCH; check the relay before blaming the file.
• ECU not recognised on the bench — the 5NR2 needs the ignition line and the correct ground; follow your tool’s pinout for the Marelli 5NR.
• Immo light on with a running engine — normal on a UCH that no longer receives a reply; it does not affect driving.

Getting the right file

Browse immo off files for Renault and search 5NR2 plus your part number. If your exact variant is missing, send the original read through the file request form; the immo off version is prepared from your own file, so the fit is guaranteed.