Moilten metal on 3rd O2 sensor

[lvangundy]

I replaced my 3rd sensor found this. We thought it was lead so we heated it up but it didn't melt - is it platinum? Or melted stuff from inside the cat? WTF?

[shorod]

Wow, that's interesting! Is the "clean" metal of the sensor around this from where you tried to heat it up, or did it come out of the car that way? As smooth as that metal looks it must have been really hot when it hit the O2 sensor. Was any exhaust welding done near that sensor?

-Rod

[lvangundy]

Good guess - there was welding done for a wideband O2 sensor but it was in front of the first cat, seems hard to imagine it traveled so far. You're probably right though.

[shorod]

It does seem hard to imagine that weld would make it through the converter and still be hot enough to bond to the sensor.

-Rod

[jdmccright]

That's the cat's ceramic internals melted and blown onto the downstream sensor. It'll look metallic from the platinum catalyst. Time to replace the cat and check/replace the upstream ones...they're letting the engine run rich.