Hey there. I haven't got a straight answer to your question as I haven't got a Doblo yet but here are a few ideas. I'm not 100% you can do it yourself you may need to take it do a dealer, but I'm sure someone will reply soon and correct me.
If you have a diesel try turning the ignition on, then off, then on again and depressing the accelerator all the way down and back up twice, turn the ignition off, on and back off again and try now. This works on most manufacturers cars that have service indicators but I can't guaruntee it'll work on your doblo.
Sorry I couldn't be of more help, I had a search round on the net for you but didn't come up with anything.