OOps - Sorry, I thought it was flat at near 0. You are right, .8 is close to the top of the range - indicating low O2. Says Rich?
Carb cleaner, propane etc will only make it richer, probably very little effect.
That also precludes an exhaust leak on the flat bank. But if the exhaust leak was on the other bank,
that O2 sensor tells the ECM the system is lean, then the ECM would richen up the whole system
since it cannot just richen one bank only. The non flat side would toggle normally (reading the false oxygen,) but the other side would see rich - as it does.
The non-flat side would be acting
normal, toggling normally trying to compensate for the exhaust leak
. But since the entire system richened up the flat bank would "see" reality
and indicate too rich.
How 'bout unplugging an injector on the bank that's showing flat? That should put extra O2 into that bank and cause the flat bank to start toggling, or at least go high? That would prove the sensor is doing it's job correctly.
The engine will probably run very rich when you unplug, and a lean code may set. Funny how sometimes you have to think backwards.
He He - in other words, look where it "seems" OK.
I never tried an infrared light to look for smoke. Seems like the smoke would have to convert the light to visible light to see it. But with the yellow goggles it may be interesting. I'll have to try it.
I don't think the 10 hour deep cleaning will help in this case, but it's certainly worth a try.