04 5.4L Oxygn Sensor Change
 

Hello Folks,
I've had a couple of P2196, P2198 incidents in the past 2 weeks so I thought its time to change the upstream O2 Sensors after 139K miles. My auto scanner has been seeing erratic LTFT readings where sometimes its rich, sometimes its lean. (+26/-26).

I did not have to remove anything or did not have to jack up the truck. Slide Under the truck and did it one by one starting with the easier one at the driver side to gain confidence :-) I had to run the engine to operating temp to be able to get both out. They wont budge when cold :-( Even if sprayed with PB Blaster overnight!

So here are the two ones after pulled out. Both are covered by like a white substance. Prior to the issue, I added gas additives twice in one oil change interval.

What do you think is the potential cause of failure based on the condition? Age, gas additives, leaks?

Thanks..

https://cimg2.ibsrv.net/gimg/www.f15...352a552fa.jpeg