Siemens MS 40 Engine ECU Repairs

Siemens MS40 Engine ECU RepairsType: Siemens Engine Management
Fits: BMW 320i / 520i
Engines: E34 / E36
Year: 1993 – 1998
Ref: ECUT323195

Note: This ECU may also fit other models.

It is a Siemens MS 40 ECU and we are able to fully test and rebuild these units.

Common part numbers associated with this type of unit

Siemens NumberOEM NumberPriceWarranty
5WK9 0021 739 855£POA12 months
5WK9 0031 744 597£POA12 months

We are able to fully test and rebuild these ECU’s with a 12 months warranty and all within a fraction of the price of a new unit. Our typical turnaround time for this type of ECU is just 3-5 working days. If you’re unit is found to be faulty and cannot be repaired, we may be able to offer a replacement unit and code it to your vehicle – making it fully plug & play.

2 thoughts on “Siemens MS 40 Engine ECU Repairs

  1. Hi,

    My unit is a SIEMENS 5WK9 002 MS40.1 with part number 1 738775.9 . I purchased this second-hand unit to replace the original on my 1993 E36 320i which had been damaged due to water ingress during a violent and very wet storm. LIttle did I know that the ‘new’ unit (purchased from Eastern Europe) also had water ingress but it seemed to work on my car just fine. Today while trouble shooting an issue that was unrelated to the issue discovered here, I opened up the unit and found water ingress had occurred too. I tested the spark plug plugs (the plugs that plug in to the spark plug coil) and found that cylinder 4 (from the front of the engine) was not firing. The spark plug itself looked brand new and had obviously not fired since it had been installed (along with the DME from Eastern Europe). The diagnostic port is not able to work in the car (OBD I) and I haven’t figured out if it is due to the car wiring or the faulty DME unit, so there may be other issues that need testing for apart from the spark plug coil not firing. What would the service cost to repair my DME unit? I live in Canada with family in the UK (in case you need to send the unit to a local address).

  2. Hey!
    Thanks for reaching out.
    Your enquiry has been forwarded to the relevant department & they will contact you soon via email.

    ECU Repairs

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