A few days ago I noticed my x-type was not decelerating when in 4th or above gear. I thought I accidentally put the cruise control on, but it wasn't the case. It can actually accelerate a bit - pretty sketchy!

A day or two before this I saw amber notice light for DCS system fail appear, but if was gone on next engine start up, so did not pay much attention - last few week were wet and cold, so just reckoned could be a small short (I am having ingress problems are rear parking sensor has been misbehaving if I drive in the rain for a while.

Any suggestions what it could be and how to diagnose/fix it?