Meg 2.7 primary handset
Rev C+ hammerhead (I think)
You can get 0.0 on ppO2 (on one or more cells) and still get a mV output on that cell plus the other.
If for instance you have:
1.19, 0.0 , and 0.0 on ppO2
and yet have
49, 52, and 51 mV on three cells
Are you going to bail, SCR, or feel fairly safe running manually that you are at roughly ppO2 1.2?
For me on an OW trimix dive I would bail and just go up. Its not worth mucking with on the bottom accumulating deco time.
For me on a 32% dil cave dive (i.e Ginnie or Jackson Blue) I would dil flush to confirm the cells are "alive" and responding, then stay on that loop and run it manually as I exited. Watching not just cell1 but that cells 2 and 3 were comparable too. While I could go SCR, that wouldn't really make me feel any safer, especially coming up shallower.
If the cell values were all crazy up and swinging all over the place I'd bail - since in my experience that indicates the cells are flooding. But a flat zero (ppO2 & mV) indicates a wiring issue, whereas a flat zero with a mV output still is a good hint of lost calibration, flash memory failure, or internal processor issue. But I am not especially skeptical that those 52 and 51 mV values are way off base. Plus I can double check that they are actually responding by doing the dil flush.