Old WBO2 sensor calibration issues, may help someone troubleshoot problems:

Intermediate nernst_dc_target values resulted in wavering (by about 0.2V, instead of the max 0.1V allowed maximum) Nernst voltage. When nernst_dc_target was raised to 0xBD, Nernst voltage was dead steady at 4.47v (maybe pump was railed at max FF?).

WBO2 testing page says I need 3.96V+0.45V=4.41V sortof steady, so lowered nernst_dc_target to 0xB7, but voltage started to waver again. With values where Nernst voltage wavers, pump value (on mlp07 of LCD) is a value such as 0xC3, jumps to FF briefly, then back down to 0xC3 (0xC3 is just an arbitrary number. actual value is above 0xC0, but I don't remember what it was).

When measuring nernst and pump-, I have varying values. I think the values i measured were bouncing between 120mv and 150mv. They are written down at home, I will post later.

I changed wbo2_pump_pidki from 0x40 to 0x20, but didn't see a difference in voltage values. Should this affect the bouncing of voltage up and down when measuring nernst (to ground) voltage and nernst to pump- voltage?

yes, it sounds like a WBO2 PID configuration issue (oscillation), because your WBO2 pump (HW) seems to react. Play with the values, especially pump_pid....

eg. try this:

Above suggested settings work well so far. Only had to adjust the wbo2_calibration and bring nernst_dc_target back down to reasonable values.