Ford Escape won’t pass smog

I have a Ford Escape that has been sitting in my driveway for years because it won’t pass smog. It ran just fine before years ago it didn’t pass smog. Smog testers have no idea why it won’t pass smog. They don’t see any clear signs as to why it won’t pass smog. Is there any solutions to get my Ford Escape to pass smog? I’d like to drive it again and be able to tow my boat etc. Is there anything I can do or install on it to bypass the exhaust system so my Ford Escape can pass smog? Any advice would be greatly appreciated