If you own a BMW E46 it is a good idea to check your catalytic converter at least once a year. While the catalytic converter is often created to be durable, it can become corroded or even be punctured and stop working. The most obvious sign of a bad catalytic converter is a rotten egg smell. If you somehow miss that symptom, you may also notice a big jump in how much fuel your car uses or a backfire when you accelerate. Fortunately, you can remove the catalytic converter with a few small steps.
Put on your eye protection. You will be looking up at the catalytic converter as you are working on it so the likelihood of road crud falling into your eyes is very high.
Disconnect the battery by loosening the battery cables with your socket wrench and pulling them completely off the battery. While it is very unlikely that you will receive an electric shock while working on your catalytic converter, it's a good idea to eliminate the possibility.
Jack your BMW E46 up with your jack. Be sure to place the jack under the metal part of the car's frame. You will damage the body of the car if you try to jack it up by placing the jack under the body.
Follow the exhaust pipe from the rear of your E46 to about three-and-a-half feet towards the engine. This is where your catalytic converter is located.
Examine the catalytic converter and note that there are four bolts. Two on the front end of the catalytic converter and two on the rear end.
Loosen all four bolts by turning your socket wrench in a counterclockwise motion.
Remove the catalytic converter by grasping it on both sides and pulling it straight down and towards you.
Tap the catalytic converter gently with your hammer in multiple spots if it seems like it is stuck. Sometimes corrosion and road debris can cause the catalytic converter to adhere to the exhaust pipe. Tapping it with the hammer can loosen it up.
- "BMW 3-series Automotive Repair Manual 1999 through 2005"; Haynes North America; Robert Maddox; 2005