Mmmmmm yea going to pull my mufflers off. See if it helps that will be my step one. I am thinking back I think my problems started right after adding mufflers...

had no choice, checked with lightning and thats the exact location they install at time of build...I cannot believe that there is not a 02 that would not live getting wet at times...when we pulled it out after getting back looked fine...thing that maybe the water cracked the porcelain that we cannot see...

as others have said, this is a common problem. I have a holley computer and use their sensors since they come with the correct connector to plug into the computer harness. after running in the driveway with a lot of water going through, I usually notice the O2 getting rich even though I have not change the tune. I have CMI sport tubes with the factory welded O2 bung on the odd side. supercharger is the new 4.5 whipple. about 1080 hp. I have 2 sensors, one is a spare. each time one goes rich, I either change to the other or dry it and buff off any carbon. I also leave the sensor in while running the boat much of time because the holley continues to tune in closed loop. in each case, over 2 years, the sensors have recovered when dried and cleaned. I doubt that the holley O2 sensor is unique or that they even manufacture it.

are you certain that they are really dead or just wet?

Let me see if the set at the shop has modifications. There have been a couple sets through the shop and all have had some sort of reversion. Large cams and small cams. JimV has welded the tips up and then added water dumps out the back/side of the boat. This is more for water intrusion into the engine then saving O2 sensors so watch for that.

I've burned up two now. First one was completely my fault as the tail pipes I have had the bung at 7 o'clock - condensation killed it. Moved it to about 10 o'clock and worked great for about 5 hours and then shortly after I launched one time it started reading full lean - swallowed a wave up the tail-pipe. Both times, when I blew out the O2, water came out the small holes. Since then, I close the mufflers (switchable) when launching, backing, and coming off plane. Since doing this, 20 hours trouble free. BTW, I too am running the Holley system. Holley uses a Bosch LSU4 O2. Since Holley's version is not readily available at local auto parts store, I have bought the Bosch 17014 (available at most any auto parts store cheap - $46) and just splice the Holley plug from the bad O2 sensor except I keep the cal resistor from the new O2. The sensor is not identical, but it has worked fine for me. Since then I have ordered a new Holley version and just keep the 17014 as a spare.

yes, ours are dead...will show either totally rich or totally lean, and shows need calibrate, which they will not do....

Yea my sensors are bad I did the brake clean in a rag test. They are junk, so new sensor and pull mufflers off and head to water.......
Skydog.

I have recommended this part before and in fact use it. I highly recommend it. I did a direct A / B comparison with the same tune both with and without this heat sink / extender and it had no affect on the AFR. It has a pitot tube like inlet which needs to be directed into the exhaust stream and prevents and reverted water from coming in contact with the sensor.

With the OP using silent choice I highly suspect he is having a reversion issue.

I used that extender and water still got in it

or you can go to your local NAPA store and use the spark plug anti Fowler kit