why does the check injection light come on in my Modus when i reach 70mph ?

Having recently had the timing belt fitted and a new clutch on my 1.5 diesel modus 05 i now find that when driving at between 65-70 mph i have a dash light on saying check injection , when i slow down it goes off, it never happened before having the work carried out,could it be just a wire that has been disturbed or knocked off .Thanks in advance if you can put my mind at rest.