14 December 2012

Mercedes E430 W210 M113.940, 205 kW 1999

Engine stalled randomly. Could be impossible to start for a longer period of time.

I had some difficulties with my E430 (W210) 1999.
When I tried starting the car the engine was not turning over. In fact nothing happened at all, except some kind of "humming noise" and the lights in the instruments came on. I could leave
it for a while and try again and it would start and runs like it should. After that it could start maybe 5 or 6 times and then fail again.

  • Battery was fully charged
  • I changed CPS (Kurbelwellensensor)
  • I changed K40 relay unit (A 000 540 00 72)
  • Removed and checked the ignition switch

The relay K40 (A 000 540 00 72) unit (yellow circle) was not closing when it had the starting issue. When it was starting, the relay was closing as well.

The fault was found in the ECU. It had a bad soldering point at the EEPROM (yellow circle).
ECU: Mercedes number: A 026 545 69 32. Bosch number: 0 261 206 303. The same ECU is used in other Mercedes, 8 cylinders as well. For ex. ML 430.

In case of replacing an ECU you have to keep in mind that the door lock (driver side), ignition switch and the ECU has to be paired together. It means, copying immobilizer data from the old ECU to the new one.


  1. thanks for the info, this has had the lesson for us ....

  2. Hi there,

    Been searching for the past week and stumbled across your blog. Breath of fresh air :)

    Now for my humble request .. I have the same ECU with a decoupling capacitor to the driver IC of the throttle body driver. Grateful if you could get me a close-up photo of the underside of your ECU.

    Bears on me sometime :)

    1. A gentleman and a scholar .. that's what you are good sir :)

      Now I know what it looks like, the next challenge is finding out the actual of the cap.

      Anything I can do, I'd be more than happy to help .. all you have to do is ask.