W204 C200 CDI Lack of power after injector seal change

[iDevonik]

I just had my injector seals changed on my PFL W204 OM651 C200 CDI since they were leaking and now the car has a lack of power (feels like limp mode). Mechanic says he can’t find no diagnostic faults on his Autel scanner. Any suggestions on the possible fault? Car drove fine before the injector seal change.