That white thing is one half of the aluminum heat shield that covers the catalytic converter. Years of salt, rain, and snow, had corroded all the bolts holding it on. The only thing keeping it attached was the oxygen sensor cable. There was a whole in the middle of the heat shield that the sensor and cable stuck through. It sounded horrible when the thing rattled around and I was afraid it might damage the sensor. First I tried to take off the sensor but I couldn't get a wrench on the nut. Next I thought about disconnecting the sensor cable and pulling the shield off but I couldn't really get my hands in their and got worried that I might not be able to reconnect things. Finally I went to walmart and bought a 3.97 pair of tin snips and just cut the thing off.
|Free of rattling shield|