i have a 2004 1.7cdti design 100ps,i have an issue in the the eml comes when under load,never when revving high and it will not come on in normal driving unless accelerating from low revs,the fault i get is p0234 overboost.i have replaced the boost sensor and the other sensor as well as the wiring plug,i have replaced some of the vacuum pipes and still no change,i have stripped the turbo down and gave it a good clean,there is no play in the turbine wheel and the vanes are moving freely,with the engine running you can see the vacuum diaphram moving freely with no stickiness to be seen,i dont want to spend a lot of money on a replacement turbo and it does not solve the problem as i have already spent over £250 on the car,my alternator is a cheap ebay item which chrges ok but could a low vacuum pump pressure cause the problem? ever since the alternator was fitted i have had a whistling noise from it,not sure if it is related when i drive from low revs with nothing when cruising,any help would be appreciated