Porsche 911 996 986 ECU Immobilizer Control Unit 996.618.604.00

996.618.604.00 is a critical electronic component found in the Porsche 911 (996) and Boxster (986) models, specifically for the “M60” frequency range (typically 315MHz or 433MHz depending on the region). This unit is the “brain” of the car’s security system.

Technical Function

This module—often referred to as the Alarm Control Unit or M-Unit—is located under the driver’s seat (on LHD cars). It manages several vital security and convenience functions:

• Immobilizer Handshake: It communicates with the transponder chip in your ignition key. If the codes don’t match, the ECU will not allow the engine to start.

• Central Locking: Controls the power locks and alarm sensors.

• Remote Entry: Processes the radio frequency (RF) signal from your key fob.

Critical Issues & Vulnerabilities

The most common reason for looking up this specific part number is water damage. Because it is mounted on the floorpan under the seat, a clogged cabriolet drain or a leaking door seal can easily flood the unit.

Symptoms of a failing 996.618.604.00:

• The car cranks but will not start (immobilizer active).

• Windows dropping or rolling down on their own.

• Remote key fob stops responding.

• The horn honks once when locking (indicating an alarm “zone” is open or the module is faulted).

Replacement & Programming Requirements

You cannot simply “plug and play” a used 604.00 unit. These modules are digitally locked to the car’s VIN and the engine ECU (DME).

Technical Specifications

• Voltage: $12\text{V}$ DC

• Manufacturer: Typically manufactured by Bosch or MPT for Porsche.

• Supersessions: This part number has several revisions. Ensure the hardware version (HW) and software version (SW) on your sticker match as closely as possible if you are attempting a data clone.