BMW 2004 645ci Active Steering Warning Light....

There is a simple test you can do o determine if it is a freak light or not. If you disconnect the battery negative connection for say 30 minutes that will reset the computer and when you reconnect the cable and run the car the light will either stay out if things are OK or it will return if there is a hard problem. If I had the car I could tell you why, but without scanning the memory there is little I can do for you from here!

Is it likely that will cause other problems ie devices that would need to be re set and memories lost? Kind Regards Martin

My 850 does the same thing if it is not used for some time. 3-4 weeks maybe. restarting eliminates the warning and away we go. My system is hydraulic power from the power steering pump. I think it just thinks it takes too long to charge up and trips the alarm. Your hard lock may have drained the power assist down then when started took too long to recover. If it recurs you have trouble. If brakes feel "off" or really hard you really have trouble. Good luck.

Thanks It has indeed 'solved' itself,it was just a bit unnerving. I've just changed a Mercedes 2001 S 430 for the beemer and I am a little concerned about beemer reliability although having said that the Merc was getting electrical/mech probs (at 96K) rusting body was its real problem.I should have done a bit more homework!! Many Thanks.Would disconnecting the battery cause any other 'problems'?

Disconnect the battery and you wil probably delete the radio presets, (no big deal), but you may have to input the radio alarm code. The emmissions will go to factory default values and you may run "off" until the computer recalibrates (usually within a few runs of the car) I don't know if the newer BMW's have other things that get reset.