We were called to replace a engine control unit of a Mercedes Benz W204 C250 CGI with the 271.860 engine by another workshop who had already diagnosed the issue after doing relevant tests and concluded the ECU needed replacement due to a cylinder 1 misfire after the engine became warm.

As this is a relatively common issue on the Benz equipped with the sim271de2.0 ECU - the choice was to either perform a board level repair or purchase a brand new control unit or a working secondhand control unit.

As the workshop had already purchased a complete lockset, it did not come with the ELV/steering lock which would not allow the ignition to turn on or start the vehicle - as we at Moks Auto do not believe in changing parts that are not needed to changed, we restored the original lockset which included the EIS, and key.


The donor ECU was renewed on our bench and ready for programming to the vehicle.

We installed the ECU back on the vehicle, flashed and coded the control unit and adapted the drive authorisation system. The vehicle was started and had no misfiring after warming up and was tested on the road.

The workshop owner was relieved to have his donor ECU running without the need of the complete lockset.

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