Q: Rattling on a 2005 Subaru Forester

Yes, the catalytic converters would often rattle. Catalytic converters look like mufflers but they are not. They have platinum inside these ceramic pieces and the hot air goes through them and burns hydrocarbon. What happens is, the ceramic parts start to break and then they rattle and go against the metal parts of the outside shell. Take a little hammer and gently hit the catalytic converter. If it rattles, then those are the metal pieces.

You could also look at the heat shields around it because a lot of the exhaust parts have heat shields that are welded on and stamped. A lot of times, those little spot welds break and start to rattle and you’ve got to re-weld those things back on again. If you’d like to have the faulty part verified by a professional, have a technician from YourMechanic inspect your car’s rattling noise for you.