I have a nissan altima 2003
My problen is ingine service soon star today and my mofle make noise help please

The cadilac converter is part of your exast system and if it is wore out the sensore that is attatched to it will signal to your dash. Take your vehicle to an autozpne and have them run a test on it for free. Get the part and change it or have someone else change it for you. Old one will need to be cut out and new one welded in.