Check Injection?

Just purchased a 2003 megane 2.0 Dynamique convertible, and am occasionally getting the message "CHECK INJECTION" along with the SERVICE light. And when this happens,it is very jerky when pulling away in first gear..........UPDATE ...........Took it back to the guy I bought it from, (still in the 28 day warranty). Drove 60 miles to his garage, and it never came up with the problem. He put it on a computer,cleared the codes and we went for a run in it, and then he plugged it back in,and it showed no faults.
Drove 60 miles home,no problem. Two weeks later I have got the toxic fume light and service light on constantly and yesterday the check ignition light is back on,along with kangaroo performance in 1st and second. Any ideas ?????
Was wondering,I have RAC recovery,will they come out and fix it ?