dealer replacing defective control bar front any relation to problem??
check engine light on for months what is problem possibility and cost on 2003 Subaru Forester
So many possibilities ...endless..you need some basic dignosis first. The computer system sets fault codes that start the diagnosis process...most of the time its not very involved but the longer you ignore the problem depending on what the cause is it could in some cases leed to other problems. And as to you other question its very unlikely.
go to auto zone and have codes read for free and post the numbers and we can advise.