Okay, I'm no expert, but this is what I know of the Motor Control System Failure warning (MCSF). But before my experience I will say that there are quite a few threads on this on this site, and I would recommend doing a few hours reading on it as there are some good points / ideas on this particular fault.
Now, this is what I have encountered. I have had the MCSF error a few times, the dealer did a lot of warranty work replacing various sensors and the cat etc, but each time the error would return after a week or so. I will point out that I experienced no loss of performance - unlike some with this error. They managed to get in top of it for a few months. I did read a lot on battery issues causing faults, however mine was still in the 'green', though I did notice some slow cranking and did have to reset the a/c temps at each start. Having run well for another six months I hd washed the car and parked it in the garage the intention of giving it a polish. It was there for a couple of weeks waiting before I went to use it. Very slow crank on startup, and had to reset the a/c temp and dates/time on the trip computer, then a day later the MCSF. Got the AA chap out to replace the battery, no point in running the thing fully flat. He checked the old one, it was sufficient voltage but failed to maintain charge on startup - so a battery fault. New one went in, cranks strongly, no longer have to reset the a/c, and the MCSF cleared after a few runs.
Now, I am not saying that this is your particular issue, but it may be worth a try - particularly if your battery is old and you have noticed some annoying a/c, trip computer resets etc like I did that may be signs of a failing battery.