[Brian_C]

With the recent bad weather I had some water ingress into my ECU on my E91, initially the car wouldn't start and had no connection to ECU via diagnostics, I gave ECUtesting a ring and they suggested possible water damage, so I removed the ECU and noticed water definitely got in so removed the ECU cover and the exposed electronics were indeed corroded. I read on another site a member had identical problem and cleaned off the corrosion with alcohol wipes so I done this, but noticed some pins still look corroded, put tried it in the car and it started with no warning lights...result!! I can now use INPA to read errors again and it shows 1 error ... 46D1 DDE: Control Unit, Internal 4

Any ideas of what this error is, the car probably feels slightly down on power but hard to tell as I didn't drive it in two weeks, also the car was remapped if that makes any difference.

[Sensible_]

I take it you cleared error and it comes back?

This fault code relates to the DDE/DME (ECU) MCU corruption. You may need write a good eeprom to the MCU with correct checksum etc etc...

XPROG and BDM is your friend here

[Brian_C]

Originally Posted by Sensible_

I take it you cleared error and it comes back?

This fault code relates to the DDE/DME (ECU) MCU corruption. You may need write a good eeprom to the MCU with correct checksum etc etc...

XPROG and BDM is your friend here

Thanks for the reply, yes I've cleared the codes and it reappears immediately. So it's looking like only a software problem yes? And writing a good eeprom to the MCU would that affect the map on the car? Sorry if these questions sound stupid, not too well up on car electronics or programming. And if so is it best to leave the person who originally remapped the car sort this error, it was a custom map as opposed to a generic map so the tuner is quite knowleagble in that area.

[Sensible_]

Originally Posted by Brian_C

Thanks for the reply, yes I've cleared the codes and it reappears immediately. So it's looking like only a software problem yes? And writing a good eeprom to the MCU would that affect the map on the car? Sorry if these questions sound stupid, not too well up on car electronics or programming. And if so is it best to leave the person who originally remapped the car sort this error, it was a custom map as opposed to a generic map so the tuner is quite knowleagble in that area.

It depends. Did you take a photo of the board? If there is hardware damage then you may suffer recurring / intermittent problems. Really the board should be tested in a lab to ensure all connections are working correctly. However a new ECU costs an arm and a leg so you have nothing to lose.

Your tuner sounds quite smart. maybe he even has an original FULL backup from when the car was mapped?

[Brian_C]

No sadly I didn't take any close ups of the board but one IC in particular had probably 3 pins which I was wary of and still looked corroded after cleaning, I do personally know someone who deals with circuit boards as a living for wireless antenna, he could possibly check out the connections in questions for me in his workshop?

In the meantime I'll give my tuner a ring and ask his opinion also, I know he definitely keeps the original map from all the cars he does work on but it may not be the full original backup.

[Brian_C]

Also after the driving the car another 10 miles or so, it is definitely down on power under 2500rpm, but once it hits 2500 it flies as expected

[Sensible_]

I would definitely get the board to your friend. I don't see why it couldn't be repaired.

The loss of power could be be related to the MCU being corrupted hence effecting your map.

Good luck. Hope you get it sorted

Also, you may want to consider cloning your ECU. This is becoming popular now so that you have a dedicated mapped ecu and a stock one which are interchangeable. They would also act as a spare should one fail.