1999 Mercedes Benz 320e exhaust

If you are hearing a rattle from underneath the vehicle it is more than likely a faulty catalytic converter. A way to be sure is to get under the vehicle with a rubber hammer or malet. Hit the cat with the hammer. If you hear rattleing in your cat then it is no good. Replacement of the catalyst will require removeal of the exhaust from the flange right before the cat to the flange before the muffler. There will be two bolts holding the catalytic converter in at these two flanges. Remove the four bolts as well as the two bolts that mount to the transmission bracket. Remove the O2 sensor connectors (one is located on the right (passanger side) upper firewall. The other is mounted to the side of the transmission. Disconnect the electrical conenctors and remove the O2 sensors with a 22mm wrench. Reinstall the O2 sensors into the new cat and reinstall in reverse order. Note: exhaust bolts can be difficult to remove due to rust. Get some rust penetrant from the auto parts store and spray all the bolts you will be removing with it. Let sit for a few minutes then remove the bolts. This will ensure ease of removal and will held with not damaging any bolts or nuts.