Mazda 2 1.6 Diesel engine revving up on its own!

Hi all,

I have a Mazda 2 1.6 diesel sport 59 plate with 65K miles on it that revs up on its own after a cold start, not every day but most days.

I have to quickly switch it off and then when I start it again it is fine until the next day or next cold start.

Sometimes it will rev up before I even move off the drive and other times it will be ok until I get about 100 yards along the road.

It had a code reader on it and 3 codes are stored U2100/P0606/P062B any help would be appreciated

Thanks