octavia 4x4 1.8 t engine fault code (timing to far retarded)

I have been getting a fault code saying that the "timing to far retarded", the light has come on twice now both reporting the same fault. My local garage has had it for a week but can't find anything abnormal. The fault does not come back quickly as in the wife uses it for work and drives like a woman should. In January this year the oil stainer was blocked so this was sorted. The fault has re-appeared last night, after driving politley around town I then took off from the lights and put the engine under aload of torque and the engine light came on. it runs ok it not lumpy, pinking, etc.

Any ideas folks!!!