How serious is this?

BMW fills these boxes with "lifetime fluid". It has to be changed every

If the supply voltage to the gearbox ecu is low it'll cause an error. This can be caused by a bad alternator voltage regulator or a dying battery.

New fluid isn't going to correct a fault like this. If you believe it's needed it must be done as a preventative measure.

First thing to check.

Indeed - fault will go away if battery is charged and engine restarted.

If it doesn't then you have a hard fault (like a snapped band).

messagenews: snipped-for-privacy@unixnerd.demon.co.uk...

feed back that it could be any of the following:

1. a "bad alternator voltage regulator"
2. a battery that may need recharging
3. New fluid to the box.

remedied. Could there be any damage to the transmission? If so how bad?

Cheers

The same thing happened when I pulled out of my driveway in my '04 X5 with the same engine about 18 months ago. It would only limp along at low speed and I had the same "failsafe" warning in the dash. BMW towed it in and hooked it up to the computer. 5 minutes later I was back on the road. The computer reprogrammed whatever caused the fault and no other service was required. It was either covered under the warranty or it may have been a recall since there was no paperwork. Have you checked to see if you have any transmission recalls (or TSB's) on your car?

Dan

You haven't answered the question about whether the fault goes away if you stop it and start it.

If it goes away - take it easy and get the codes read.

If it stays - drive it very gently to a dealer.