speed wrxer

Hey guys.I recently put my stock tbe on for smog testing.now I'm getting cel P0136 which is rear o2 sensor circuit malfunction.I checked all the electrical connections reset the ecu and still get the cel.I took the sensor out to visually inspect it.It seems to have something rattling around inside it.Is this normal?I'm thinking its toast.Should I go ahead and replace it?Any help would be greatly appreciated!

yanimaya

yes, you should replace asap, that O2 is already dead. good sensor should not have anything lose inside of it.