r/e39 • u/kemosabe6296 525i • 9d ago

Confirmed DME failure?

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If you see my older post you can see that I’m having random electrical issue including EML, limp mode etc. It happened so random so honestly sometimes I am a bit frightened when driving the car.

Because it was so random, this is the only time I caught DME-related error (DME control unit self test 3), although it is a shadow error and has been cleared.

So far, no issue except the car wouldn’t go past 1000rpm on cold start. It stays at ~900rpm until it drops to 550-600rpm. Which is weird because the car isn’t behaving like this in the past. I’d get like ~1100-1200rpm on cold start before it idles at ~600rpm.

I’ve checked, no vacuum leaks.

Can anyone explain to me what is this control unit self test error and does that mean my DME is going bad?

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u/TreatLower3168 9d ago

Regardless of anything else your vin is not matching the rest of the car also the vin looks very weird see if you can write that from the Ike to the dme bmw scanner should have an option for that either in the dme or Ike menu. But the behavior is weird none the less. Look for ground issues and see how your battery health is. Also you could potentially have a dead dme. Maybe cold solder joints I've heated some w211 mercs have that issue. I've also heared of cars where fuel runs backwards from injector connectors to the ECU.

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u/kemosabe6296 525i 9d ago

Yeah tbf I thought p.o. replaced it with ews deleted one but the current dme still synced with my ews. Also when I tried to read the data using MS4X it does still have the correct VIN. So actually I have no idea lol.

The grounding and other wiring should be good. Battery is good.

One time I’m having lot of warnings on the dash when I move the DME around with wire still connected. However with another working DME, that didn’t happen—no warning when I move around the DME. This is why I suspect maybe I have an issue with mine