O2 sensor leak

[89K5guy]

I have an exhaust leak right around the O2 sensor on the driver's side header
pipe.I checked the weld around the bung that was added in order to install the sensor and it is a good solid weld ,no rust.It just barely ticks but enuff you can tell there is an exhaust leak.Is there any high temp thread sealer
available for this?I know that a code 44 can be thrown if there are exhaust leaks and especially if the leak is right around the O2 sensor.I cleaned and sanded and filed the bung where the ring /washer seals the O2 sensor at the
top of the bung but the leak seems to be coming from the threads.As you screw the sensor into the bung the tick quiets down but you can feel little
puffs of air from around the sensor when it is tight.Any help/ideas would be greatly appreciated. Brian

 

[dyeager535]

I don't know that there is any other kind, but is it possible it's the wrong threads? IIRC they are M18x1.5

 

[89K5guy]

I am eventually going to replace the headers anyway but till then i need a temporary fix for this sensor leak.You could be right about the threads but when you try to move the sensor side 2 side , the threads seem to bite very good as I tighten it.I am so perplexed.