Siemens Ms 43.0 Engine Control System: Introduction

1999 BMW 328i 2D Convertible, AutomaticSECTION Introduction

This new generation Siemens system is designated as MS 43.0. 

Siemens MS 43.0 is a newly developed engine management system to meet the needs of Ultra Low Emission Vehicle (ULEV) compliancy for the 3.0 liter variant, and continue with LEV compliancy for the 2.5 liter version. This system also includes control of the Electric Throttle Valve (EDK).

The ECM uses a pc-board dual-processor control unit in the SKE housing configuration.

The MS 43.0 ECM is flash programmable as seen with previous systems.

ECM hardware includes:

Modular plug connectors featuring 5 connectors in the SKE housing with 134 pins.

  • Connector 1 = Supply voltages and grounds
  • Connector 2 = Peripheral signals (oxygen sensors, CAN, etc.)
  • Connector 3 = Engine signals
  • Connector 4 = Vehicle signals
  • Connector 5 = Ignition signals
    Fig 1: Identifying Control Unit Modular Plug Connectors
    G03396008Courtesy of BMW OF NORTH AMERICA, INC.

Special features:

  • The Flash EPROM has the capability to be programmed up to 13 times.
  • Once a control unit is installed and coded to a vehicle it cannot be swapped with another vehicle for diagnosing or replacement (because of EWS 3.3).
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.