Help bank one o2 0.00

[DaddyWood]

Hello, I'm stuck. Ho2s1 b1 reads 0.00 volts unless I create a vacuum leak. Then my volts on both up streams jumps to normal and my alphas jump to 100%. Hook the hose back up and b1 slowly goes back to 0.00. Same thing happens if I remove the dipstick. Any ideas or fresh perspective would be greatly appreciated.

[joe603]

Check out the FSMs (link in my sig). Not a mechanic, but there are a few on here.