I've disconnected the power steering lines several times when lowering subframes for transmission replacement, but cannot recall whether this is advantageous on the '06 Sonata. Check your paperwork from the transmission replacement. If there's a part number something like npnsteerfd, then it was replaced.
I don't really think whether it was replaced during transmission replacement is really the important question, though. How did the shop determine you fluid was breaking down? What tests did they run to determine this? Don't be afraid to ask these questions. What you're likely to find is that the technician sees it hasn't yet been done or that the fluid is dark in color.
Shops recommend fluid flushes and replacements because they're high profit items. Service advisors and technicians typically get financial incentives beyond their typical pay for these items. Check your owner's manual. You'll see there's no maintenance interval for the power steering fluid. So unless it's really gross, there's *no* good reason to change it.
I don't think I've recommended this repair even once on any vehicle. I will say, however, that some older GM vehicles had some steering problems that fluid flushing will help compensate for or help prevent, so it's not true that this service is *never* a good idea.
-- Message posted using
formatting link
information at
formatting link