don't know the equipment they have to do their diagnostics, but being they advertise they service mercedes, they do have some kind of equipment. In any event, I haven't even mentioned the other problems that they did while installing the new cylinder. One being, when they put the latches back in place, they did not correclty adjust them thus breaking a microswitch on one of the 2 latches. Mercedes states the roof would not unlatch nor funtion with a microswitch broken. Could these have really been pre existing as well? How could I have put my roof down if the switch was broken and the latches would not allow the roof to release? They put these latches back on when they put the cylinder back in its place. They really did a number on my car!