'07 Cobalt, 2.2L

Replacing the (whole) exhaust. I got the (heated) O2 sensors off, but the gasket ring on the downstream one is completely buggered. Short of just replacing the sensor, does anyone have any experience with, or thoughts about ..

  • Using an (18 mm) spark plug gasket?
  • Or, just installing it without a gasket?

Update: I did the spark plug gasket. AFAICT, it's working. If something bad happens, I'll update.

1 Answer 1


You don't want it to leak oxygen in through the threads as this will cause the sensor to misread what is coming through the cat. If the 18mm spark plug gasket is the same size (I know sensors have a 7/8" hex, but don't know the thread diameter), it will probably do you just fine. I would also recommend putting some copper anti-seize (nickel or aluminum will work, too, just not as well) as this will keep the sensor from getting stuck in the bung, but more importantly, will help seal it against leaks. If you can do this, ensure you don't get any on the sensor itself.

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