[boogieman065]

I'm baffled trying to chase down this code.

P0159: Oxygen sensor modulating slowly.

So far, I've changed my air oil separator (known Cayman issue to cause fouled sensors), O2 sensor, and even tried to use an O2 sensor spacer to see if I'd get a different result. The code just keeps coming back.

O2B1S2 consistent reads between .6-9v

O2B2S2 consistent reads similarly, but I noticed it'll dip to .3v for just a second.

My hypothesis is that it's not the cat (spacer would've caused a different reading?) and it's not the O2 sensor (replaced, visually looks great when I added the spacer today).

What would cause the B2S2 to drop to .3v though? Sick of this code and having to erase it. Car has 136k miles.